Hadith 1:

حَدَّثَنَا عَلِيُّ بْنُ إِسْمَاعِيلَ عَنْ مُوسَى بْنِ طَلْحَةَ عَنْ حَمْزَةَ بْنِ عَبْدِ الْمُطَّلِبِ بْنِ عَبْدِ اللَّهِ الْجُعْفِيِّ قَالَ‌ دَخَلْتُ عَلَى الرِّضَا(ع)وَ مَعِي صَحِيفَةٌ أَوْ قِرْطَاسٌ فِيهِ عَنْ جَعْفَرٍ(ع)أَنَّ الدُّنْيَا مُثِّلَتْ لِصَاحِبِ هَذَا الْأَمْرِ فِي مِثْلِ فِلْقَةِ الْجَوْزَةِ فَقَالَ يَا حَمْزَةُ ذَا وَ اللَّهِ حَقٌّ فَانْقُلُوهُ إِلَى أُدَيْمٍ

The narrator says,

"I came up to al-Reza (عليه السلام) and with me was a parchment, or a paper, in it (was written) from Imam Jafar Sadiq (عليه السلام) that, "The world is present in front of the Master of this Command (i.e. Sahib al-Amr, Imam of the time), like a half of a walnut". 

Imam Ridha (عليه السلام) said, "O Hamza, by Allah (عز وجل) that is the truth. Transfer it to a surface (i.e. make a copy of it)."

[Source: Basair al-Darajaat, Vol. 8, Ch. 14, Hadith. 2]

حَدَّثَنَا مُحَمَّدُ بْنُ الْحُسَيْنِ عَنْ مُوسَى بْنِ سَعْدَانَ عَنْ عَبْدِ اللَّهِ بْنِ الْقَاسِمِ عَنْ سَمَاعَةَ بْنِ مِهْرَانَ قَالَ قَالَ أَبُو عَبْدِ اللَّهِ(ع)إِنَّ الدُّنْيَا تُمَثَّلُ لِلْإِمَامِ فِي فِلْقَةِ الْجَوْزِ فَمَا تَعَرَّضَ لِشَيْ‌ءٍ مِنْهَا وَ إِنَّهُ لَيَتَنَاوَلُهَا مِنْ أَطْرَافِهَا كَمَا يَتَنَاوَلُ أَحَدُكُمْ مِنْ فَوْقِ مَائِدَتِهِ مَا يَشَاءُ فَلَا يَعْزُبُ عَنْهُ مِنْهَا شَيْ‌ءٌ

Narrated that Abu Abdillah Imam Sadiq (عليه السلام) said, 

"The world is present in front of the Imam like a half of a walnut. Whenever something occurs in it, He takes from it, or from its outskirts, just like one of you takes from above the table whatever you like. Nothing of it is hidden from Him."

[Source: Basair al-Darajaat, Vol. 8, Ch. 14, Hadith. 3]