The Day of death of the Prophet (saww) is unlucky

حَدَّثَنَا أَبِي رَضِيَ اللَّهُ عَنْهُ قَالَ حَدَّثَنَا سَعْدُ بْنُ عَبْدِ اللَّهِ قَالَ حَدَّثَنِي أَحْمَدُ بْنُ مُحَمَّدِ بْنِ عِيسَى عَنْ مُوسَى بْنِ الْقَاسِمِ الْبَجَلِيِّ عَنْ عَلِيِّ بْنِ جَعْفَرٍ قَالَ: جَاءَ رَجُلٌ إِلَى أَخِي مُوسَى بْنِ جَعْفَرٍ ع فَقَالَ لَهُ جُعِلْتُ فِدَاكَ إِنِّي أُرِيدُ الْخُرُوجَ فَادْعُ لِي فَقَالَ وَ مَتَى تَخْرُجُ قَالَ يَوْمَ الْإِثْنَيْنِ فَقَالَ لَهُ وَ لِمَ تَخْرُجُ يَوْمَ الْإِثْنَيْنِ قَالَ أَطْلُبُ فِيهِ الْبَرَكَةَ لِأَنَّ رَسُولَ اللَّهِ ص وُلِدَ يَوْمَ الْإِثْنَيْنِ فَقَالَ كَذَبُوا وُلِدَ رَسُولُ اللَّهِ ص يَوْمَ الْجُمُعَةِ وَ مَا مِنْ‏ يَوْمٍ‏ أَعْظَمُ‏ شُؤْماً مِنْ‏ يَوْمِ‏ الْإِثْنَيْنِ‏ يَوْمٍ مَاتَ فِيهِ رَسُولُ اللَّهِ ص وَ انْقَطَعَ فِيهِ وَحْيُ السَّمَاءِ وَ ظُلِمْنَا فِيهِ حَقَّنَا أَ لَا أَدُلُّكَ عَلَى يَوْمٍ سَهْلٍ لَيِّنٍ أَلَانَ اللَّهُ لِدَاوُدَ ع فِيهِ الْحَدِيدَ فَقَالَ الرَّجُلُ بَلَى جُعِلْتُ فِدَاكَ فَقَالَ اخْرُجْ يَوْمَ الثَّلَاثَاء


Narrated my father, from Saad bin Abdillah, from Ahmad bin Mohammd bin Isa, from Moosa bin al-Qasim al-Bajali, from Ali bin Jafar:

A man came to my brother Imam Moosa Kazim (as) and said, "May I be sacrificed for You. I intend to go out so pray for me."

Imam (as) said, "When do you intend to go?" 
He said, "On Monday."

Imam (as) said, "Why do you want to go out on Monday?" 
He said, "I want to seek blessings in it since the Prophet (saww) was born on Monday."

Imam (as) said, "They have lied. The Prophet (saww) was born on Friday and there is no day more inauspicious (unlucky) than Monday, in which the Prophet (saww) died and the heavenly revelations were cut-off and Our rights were oppressed. Shall I not guide you to an easy day on which Allah (swt) softened iron for Dawood (as)? 

The man said, "Yes." 
Imam (as) said, "Go out on Tuesday". 

[Source: Al-Khisal, Vol. 2, Pg. 385 & Qurb al-Asnaad, Pg. 299]