Hadith 1:

الحسن بن علي الهاشمي، عن محمد بن موسى، عن يعقوب بن يزيد، عن الحسن بن علي الوشاء قال: حدثني نجبة بن الحارث العطار  قال: سألت أبا جعفر (عليه السلام) عن صوم يوم عاشورا، فقال: صوم متروك بنزول شهر رمضان والمتروك بدعة، قال نجبة فسألت أبا عبد الله (عليه السلام) من بعد أبيه (عليه السلام) عن ذلك فأجابني بمثل جواب أبيه، ثم قال: أما إنه صوم يوم ما نزل به كتاب ولا جرت به سنة إلا سنة آل زياد بقتل الحسين بن علي صلوات الله عليهم

Narrated al-Hasan bin Ali al-Hashimi, from Mohammad bin Moosa, from Yaqoob bin Yazeed, from al-Hasan bin Ali al-Washa, from Najabah bin Haris:

Najabah bin Haris asked Aba Jafar Imam Baqir (عليه السلام) about fasting on the day of Ashura. 

Imam (عليه السلام) said, "Fasting on the day of Ashoora is discarded/rejected after the arrival of month of Ramadan, And what ever is discarded/rejected is a bidah (innovation)."

Najabah (the narrator) then says, "I asked Aba Abdillah Imam Sadiq (as) the same after passing away of His Father (as) and He answered with a similar answer like His Father (as). Imam Sadiq (as) then said, "As for the fast of day of Ashura there is nothing of it in the Book (Quran) and it has not come in the Sunnah, except that it is a Sunnah of aal-e-Ziyaad upon the killing of Husain bin Ali (عليهم السلام).

[Source: al-Kafi, Vol.4, Pg. 146]

Hadith 2:

عَبْدُ اللَّهِ بْنُ سِنَانٍ قَالَ: دَخَلْتُ عَلَى سَيِّدِي أَبِي عَبْدِ اللَّهِ جَعْفَرِ بْنِ مُحَمَّدٍ عَلَيْهِمَا السَّلَامُ فِي يَوْمِ عَاشُورَاءَ فَأَلْفَيْتُهُ كَاسِفَ اللَّوْنِ ظَاهِرَ الْحُزْنِ وَ دُمُوعُهُ تَنْحَدِرُ مِنْ عَيْنَيْهِ كَاللُّؤْلُؤِ الْمُتَسَاقِطِ فَقُلْتُ: يَا ابْنَ رَسُولِ اللَّهِ مِمَّ بُكَاؤُكَ؟ لَا أَبْكَى اللَّهُ عَيْنَيْكَ، فَقَالَ لِي: أَوَ فِي غَفْلَةٍ أَنْتَ؟ أَمَا عَلِمْتَ أَنَّ الْحُسَيْنَ بْنَ عَلِيٍّ أُصِيبَ فِي مِثْلِ هَذَا الْيَوْمِ؟ فَقُلْتُ: يَا سَيِّدِي فَمَا قَوْلُكَ فِي صَوْمِهِ؟ فَقَالَ لِي: صُمْهُ مِنْ غَيْرِ تَبْيِيتٍ، وَ أَفْطِرْهُ مِنْ غَيْرِ تَشْمِيتٍ، وَ لَا تَجْعَلْهُ يَوْمَ صَوْمٍ كَمَلًا وَ لْيَكُنْ إِفْطَارُكَ بَعْدَ صَلَاةِ الْعَصْرِ بِسَاعَةٍ عَلَى شَرْبَةٍ مِنْ مَاءٍ، فَإِنَّهُ فِي مِثْلِ ذَلِكَ الْوَقْتِ مِنْ ذَلِكَ الْيَوْمِ تَجَلَّتِ الْهَيْجَاءُ عَنْ آلِ رَسُولِ اللَّهِ وَ انْكَشَفَتِ الْمَلْحَمَةُ عَنْهُمْ، وَ فِي الْأَرْضِ مِنْهُمْ ثَلَاثُونَ صَرِيعاً فِي مَوَالِيهِمْ يَعِزُّ عَلَى رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَ آلِهِ وَ سَلَّمَ مَصْرَعُهُمْ وَ لَوْ كَانَ فِي الدُّنْيَا يَوْمَئِذٍ حَيّاً لَكَانَ صَلَوَاتُ اللَّهِ عَلَيْهِ هُوَ الْمُعَزَّى بِهِمْ، قَالَ: وَ بَكَى أَبُو عَبْدِ اللَّهِ عَلَيْهِ السَّلَامُ حَتَّى اخْضَلَّتْ لِحْيَتُهُ بِدُمُوعِهِ، ثُمَّ قَالَ: إِنَّ اللَّهَ جَلَّ ذِكْرُهُ لَمَّا خَلَقَ النُّورَ خَلَقَهُ يَوْمَ الْجُمُعَةِ فِي تَقْدِيرِهِ فِي أَوَّلِ يَوْمٍ مِنْ شَهْرِ رَمَضَانَ، وَ خَلَقَ الظُّلْمَةَ فِي يَوْمِ الْأَرْبِعَاءِ يَوْمَ عَاشُورَاءَ فِي مِثْلِ ذَلِكَ يَعْنِي يَوْمَ الْعَاشِرِ مِنْ شَهْرِ الْمُحَرَّمِ فِي تَقْدِيرِهِ، وَ جَعَلَ لِكُلٍّ مِنْهُمَا شِرْعَةً وَ مِنْهَاجاً، يَا عَبْدَ اللَّهِ بْنَ سِنَانٍ إِنَّ أَفْضَلَ مَا تَأْتِي بِهِ فِي هَذَا الْيَوْمِ أَنْ تَعْمِدَ إِلَى ثِيَابٍ طَاهِرَةٍ فَتَلْبَسَهَا وَ تَتَسَلَّبَ، قُلْتُ: وَ مَا التَّسَلُّبُ؟ قَالَ: تُحَلِّلُ أَزْرَارَكَ وَ تَكْشِفُ عَنْ ذِرَاعَيْكَ كَهَيْئَةِ أَصْحَابِ الْمَصَائِبِ، ثُمَّ تَخْرُجُ إِلَى أَرْضٍ مُقْفِرَةٍ أَوْ مَكَانٍ لَا يَرَاكَ بِهِ أَحَدٌ أَوْ تَعْمِدَ إِلَى مَنْزِلٍ لَكَ خَالٍ، أَوْ فِي خَلْوَةٍ مُنْذُ حِينَ يَرْتَفِعُ النَّهَارُ فَتُصَلِّي أَرْبَعَ رَكَعَاتٍ تُحْسِنُ رُكُوعَهَا وَ سُجُودَهَا وَ خُشُوعَهَا وَ تُسَلِّمُ بَيْنَ كُلِّ رَكْعَتَيْنِ تَقْرَأُ فِي الْأُولَى سُورَةَ الْحَمْدِ، وَ قُلْ يا أَيُّهَا الْكافِرُونَ‌، وَ فِي الثَّانِيَةِ الْحَمْدَ، وَ قُلْ هُوَ اللَّهُ أَحَدٌ، ثُمَّ تُصَلِّي رَكْعَتَيْنِ أُخْرَيَيْنِ تَقْرَأُ فِي الْأُولَى الْحَمْدَ، وَ سُورَةَ الْأَحْزَابِ، وَ فِي الثَّانِيَةِ الْحَمْدَ، وَ إِذا جاءَكَ الْمُنافِقُونَ‌، أَوْ مَا تَيَسَّرَ مِنَ الْقُرْآنِ، ثُمَّ تُسَلِّمُ وَ تُحَوِّلُ وَجْهَكَ نَحْوَ قَبْرِ الْحُسَيْنِ عَلَيْهِ السَّلَامُ وَ مَضْجَعِهِ، فَتُمَثِّلُ لِنَفْسِكَ مَصْرَعَهُ وَ مَنْ كَانَ مَعَهُ مِنْ وُلْدِهِ وَ أَهْلِهِ وَ تُسَلِّمُ وَ تُصَلِّي عَلَيْهِ وَ تَلْعَنُ قَاتِلِيهِ وَ تَبَرَّأُ مِنْ أَفْعَالِهِمْ، يَرْفَعُ اللَّهُ عَزَّ وَ جَلَّ لَكَ بِذَلِكَ فِي الْجَنَّةِ مِنَ الدَّرَجَاتِ وَ يَحُطُّ عَنْكَ مِنَ السَّيِّئَاتِ، ثُمَّ تَسْعَى مِنَ الْمَوْضِعِ الَّذِي أَنْتَ فِيهِ إِنْ كَانَ صَحْرَاءَ أَوْ فَضَاءً أَوْ أَيَّ شَيْ‌ءٍ كَانَ خُطُوَاتٍ، تَقُولُ فِي ذَلِكَ: إِنَّا لِلَّهِ وَ إِنَّا إِلَيْهِ رَاجِعُونَ، رِضًا بِقَضَائِهِ وَ تَسْلِيماً لِأَمْرِهِ، وَ لْيَكُنْ عَلَيْكَ فِي ذَلِكَ الْكَآبَةُ وَ الْحُزْنُ وَ أَكْثِرْ مِنْ ذِكْرِ اللَّهِ سُبْحَانَهُ وَ الِاسْتِرْجَاعِ فِي ذَلِكَ الْيَوْمِ.
....

فَإِنَّ هَذَا أَفْضَلُ يَا ابْنَ سِنَانٍ مِنْ كَذَا وَ كَذَا حَجَّةً، وَ كَذَا وَ كَذَا عُمْرَةً تَتَطَوَّعُهَا وَ تُنْفِقُ فِيهَا مَالَكَ وَ تَنْصِبُ فِيهَا بَدَنَكَ وَ تُفَارِقُ فِيهَا أَهْلَكَ وَ وُلْدَكَ. وَ اعْلَمْ أَنَّ اللَّهَ تَعَالَى يُعْطِي مَنْ صَلَّى هَذِهِ الصَّلَاةَ فِي هَذَا الْيَوْمِ وَ دَعَا بِهَذَا الدُّعَاءِ مُخْلِصاً، وَ عَمِلَ هَذَا الْعَمَلَ مُوقِناً مُصَدِّقاً عَشْرَ خِصَالٍ مِنْهَا أَنْ يَقِيَهُ اللَّهُ مِيتَةَ السَّوْءِ، وَ يُؤْمِنَهُ مِنَ الْمَكَارِهِ وَ الْفَقْرِ، وَ لَا يُظْهِرَ عَلَيْهِ عَدُوّاً إِلَى أَنْ يَمُوتَ، وَ يُوقِيَهُ اللَّهُ‌ مِنَ الْجُنُونِ وَ الْجُذَامِ وَ الْبَرَصِ فِي نَفْسِهِ وَ وُلْدِهِ إِلَى أَرْبَعَةِ أَعْقَابٍ لَهُ، وَ لَا يَجْعَلَ لِلشَّيْطَانِ وَ لَا لِأَوْلِيَائِهِ عَلَيْهِ وَ لَا عَلَى نَسْلِهِ إِلَى أَرْبَعَةِ أَعْقَابٍ سَبِيلًا. قَالَ ابْنُ سِنَانٍ: فَانْصَرَفْتُ وَ أَنَا أَقُولُ: الْحَمْدُ لِلَّهِ الَّذِي مَنَّ عَلَيَّ بِمَعْرِفَتِكُمْ وَ حُبِّكُمْ وَ أَسْأَلُهُ الْمَعُونَةَ عَلَى الْمُفْتَرَضِ عَلَيَّ مِنْ طَاعَتِكُمْ بِمَنِّهِ وَ رَحْمَتِهِ‌

Narrated from Abdullah ibn Sinaan who said,

"On the day of Ashura, I came to my master, Abu 'Abd Allah, Jafar ibn Muḥammad (عليه السلام). I saw that his complexion was pale, and he was full of sorrow. Tears were dropping from his eyes like falling pearls.

I (the narrator) asked "O son of Allah's Messenger! Why are you weeping? May God never bring tears to your eyes."

Imam (عليه السلام) said to me, "Are you not aware? Do you not know that on this day, al-Husain (عليه السلام) was martyred?"

I asked, "O master, what do You say about fasting on this day?" 

Imam replied, "Fast on it, but do not make the intention from the night before, and break the fast without joy. Do not fast for the complete day; break the fast with some water after the after noon (asr) prayer. For, this was around the time on that day when the attack against the family of Allah's Messenger (عليهم السلام) came to an end, and the slaughter against them was removed.

Thirty of their companions lay killed on the ground. Their deaths were grievous to Allah's Messenger (صلى الله عليه و آله), and if he had been alive in the world on that day, He (صلى الله عليه و آله) would have been given condolences (Taziah) over them."

The Imam (عليه السلام) wept until his beard was wet with his tears. 

Then He said, "Indeed when Allah (جل ذكره), created light, he created it according to His decree (Qadr), on the first Friday of the month of Ramadan, and likewise, He created darkness on a Wednesday the day of Ashura the tenth day of Muharam according to His decree (Qadr). And for each of these two, He created specific laws and methods.

Then Imam (عليه السلام) said, "O Abd Allah ibn Sinan, The best thing one can do on this day is to take pure (tahir) clothes & wear them and comeout dressed as someone in grief/mourning."

I (the narrator) asked, "How should one dress as one in grief/mourning?"

Imam (عليه السلام) replied, "Keep the buttons undone, and roll up your sleeves leaving your arms revealed, as the grieving people do. Then, as the day carries on, go out to an isolated place, or somewhere where no one can see you, or to a secluded room, or somewhere private. Then recite four units of prayer, taking care in its bowing, prostrations, and reverence. Recite them in two units of two. In the first unit recite Surat al-Hamd followed by Surat al-Kafirun. In the second unit, recite Surat al-Hamd followed by Surat al-Ikhlas. Then recite two more units. In the first unit recite Surat al-Hamd fol lowed by Surat al-Ahzab. In the second unit, recite Surat al-Hamd followed by Surat al-Munafiqun. Alternatively, recite chapters of the Qur'an that is easy for you."

"After completing the prayers, turn your face in the direction of the grave and resting place of al-Husayn (عليه السلام), and imagine/think of the scene of his killing and that of his children and family. Then, send salutations and blessings on Him, and curse His killers, and declare your disassociation (Tabarra) from their action. By doing this, Allah (عز وجل), shall raise your station in paradise many degrees, and forgive you many of your sins.

"Thereafter, walk few steps from your place, wherever you are, while saying, 'We are from Allah, and to Him is our return, satisfied with His decree (Qadha) and submitting to His command." But when you do thism you should be in a state of intense grief and sorrow and you should remember Allah a lot and recite the verse of return a lot (i.e. We are from Allah, and to Him is our return (2:156)

(The Imam then teaches a dua to be recited on the day of Ashura which is not mentione here)

Then the Imam (عليه السلام) says, "These are better acts, O Ibn Sinan, than several greater (hajj) and lesser (umrah) pilgrimages, which you perform voluntarily, spend your wealth for, put your bodies under great strain to complete, and separate from your family and children for their duration."

"You should know that Allah (تعالى), shall grant ten bounties to the one who prays this prayer (Salaat) on this day, who sincerely recites this supplication, and who carries out these acts with certainty and belief. Among these bounties are: Allah will save him from a dishonourable death, spare him from His tests and poverty, will not allow an enemy to overcome him until his death, protect him and his children to four generations from insanity, leprosy and other such diseases, and will not allow Shayṭān and his followers access to him or his offspring for four generations."

Ibn Sinan (the narrator) said: I departed saying, "All praise is due to Allah, who favoured us by allowing us to know and love You. I ask Him for help, out of His mercy and generosity, in obeying You in the matters which are obligatory on me."

[Source: Misbah al-Mutahajjid, Shaikh Tusi, Pg. 543-547]

Hadith 3:

وَ عَنْهُ عَنْ مُحَمَّدِ بْنِ الْحُسَيْنِ عَنْ مُحَمَّدِ بْنِ سِنَانٍ عَنْ أَبَانٍ عَنْ عَبْدِ الْمَلِكِ قَالَ: سَأَلْتُ أَبَا عَبْدِ اللَّهِ ع عَنْ صَوْمِ تَاسُوعَاءَ وَ عَاشُورَاءَ مِنْ شَهْرِ الْمُحَرَّمِ فَقَالَ تَاسُوعَاءُ يَوْمٌ حُوصِرَ فِيهِ الْحُسَيْنُ ع وَ أَصْحَابُهُ رَضِيَ اللَّهُ عَنْهُمْ بِكَرْبَلَاءَ وَ اجْتَمَعَ عَلَيْهِ خَيْلُ أَهْلِ الشَّامِ وَ أَنَاخُوا عَلَيْهِ‌ وَ فَرِحَ ابْنُ مَرْجَانَةَ وَ عُمَرُ بْنُ سَعْدٍ بِتَوَافُرِ الْخَيْلِ وَ كَثْرَتِهَا وَ اسْتَضْعَفُوا فِيهِ الْحُسَيْنَ صَلَوَاتُ اللَّهِ عَلَيْهِ وَ أَصْحَابَهُ رَضِيَ اللَّهُ عَنْهُمْ وَ أَيْقَنُوا أَنْ لَا يَأْتِيَ الْحُسَيْنَ ع نَاصِرٌ وَ لَا يُمِدَّهُ أَهْلُ الْعِرَاقِ بِأَبِي الْمُسْتَضْعَفُ الْغَرِيبُ ثُمَّ قَالَ وَ أَمَّا يَوْمُ عَاشُورَاءَ فَيَوْمٌ أُصِيبَ فِيهِ الْحُسَيْنُ ع صَرِيعاً بَيْنَ أَصْحَابِهِ وَ أَصْحَابُهُ صَرْعَى حَوْلَهُ عُرَاةً أَ فَصَوْمٌ يَكُونُ فِي ذَلِكَ الْيَوْمِ كَلَّا وَ رَبِّ الْبَيْتِ الْحَرَامِ مَا هُوَ يَوْمَ صَوْمٍ وَ مَا هُوَ إِلَّا يَوْمُ حُزْنٍ وَ مُصِيبَةٍ دَخَلَتْ عَلَى أَهْلِ السَّمَاءِ وَ أَهْلِ الْأَرْضِ وَ جَمِيعِ الْمُؤْمِنِينَ وَ يَوْمُ فَرَحٍ وَ سُرُورٍ- لِابْنِ مَرْجَانَةَ وَ آلِ زِيَادٍ وَ أَهْلِ الشَّامِ غَضِبَ اللَّهُ عَلَيْهِمْ وَ عَلَى ذُرِّيَّاتِهِمْ وَ ذَلِكَ يَوْمٌ بَكَتْ عَلَيْهِ جَمِيعُ بِقَاعِ الْأَرْضِ خَلَا بُقْعَةِ الشَّامِ فَمَنْ صَامَهُ أَوْ تَبَرَّكَ بِهِ حَشَرَهُ اللَّهُ مَعَ آلِ زِيَادٍ مَمْسُوخُ الْقَلْبِ مَسْخُوطٌ عَلَيْهِ وَ مَنِ ادَّخَرَ إِلَى مَنْزِلِهِ ذَخِيرَةً أَعْقَبَهُ اللَّهُ تَعَالَى نِفَاقاً فِي قَلْبِهِ إِلَى يَوْمِ يَلْقَاهُ وَ انْتَزَعَ الْبَرَكَةَ عَنْهُ وَ عَنْ أَهْلِ بَيْتِهِ وَ وُلْدِهِ وَ شَارَكَهُ الشَّيْطَانُ فِي جَمِيعِ ذَلِكَ‌

Narrated from Abd al-Malik, who said: I asked Abu Abd-Allah Imam Sadiq (عليه السلام) about fasting on the ninth and tenth of Muharram.

Imam Sadiq (عليه السلام) said, "Ninth (of Muharram, Tasua) was the day on which Imam Husain (عليه السلام) and His companions were surrounded/besieged in Karbala and the horsemen of Shaam had gathered against Him and stationed near Him. And Ibn Marjanah & Umar bin Sad were happy due to the increasing & large number of their horsemen, and they considered Imam Husain (عليه السلام) & His companions to be weak and they were certain that no one could come to the help of Imam Husain (عليه السلام) and that the people of Iraq would not help Him."

Imam Sadiq (عليه السلام) then said, "May My Father be sacrificed for the stranger (Gareeb) who was considered as helpless/weak."

Then the Imam said, "As for the tenth of Muharram, it is the day on which al-Husain (عليه السلام) was killed, and His companions were killed around him and were looted. So, is there any fasting on that day? No, by the Lord of the Sacred House, it is not a day of fasting! It is not but a day of sorrow/grief and calamity that befell the people of heaven and earth and all the believers, and a day of joy and happiness for Ibn Marjana and the family of Ziyad and the people of Sham. May Allah be angry with them and their offspring! 

And the day of Ashura is the day on which all the parts of the earth wept except the region of Sham. Whoever fasts on it or finds pleasure/delight/enjoy in it, Allah will gather him with the family of ziyad, his heart distorted and subjected to anger. And whoever seeks to accumulate provisions in his house, Allah (تعالى) will make hypocrisy grow in his heart until the day he meets Him, and He will withdraw blessing from him and his family and children, and Satan will share with him in all of that."

[Source: al-Kafi, Vol. 4, Pg. 147]