Musnad Ahmad 353
It was narrated that Simak bin Harb said:
I heard an-Nu`man - i.e., bin Basheer - say: `Umar (رضي الله عنه) mentioned what the people had acquired of worldly gains and said: I saw the Messenger of Allah (ﷺ)  remaining curled up [with hunger pangs] all day, unable to find even the worst type of dates with which to fill his stomach.
حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، وَحَجَّاجٌ، قَالَا حَدَّثَنَا شُعْبَةُ، عَنْ سِمَاكِ بْنِ حَرْبٍ، قَالَ سَمِعْتُ النُّعْمَانَ يَعْنِي ابْنَ بَشِيرٍ، يَخْطُبُ قَالَ ذَكَرَ عُمَرُ رَضِيَ اللَّهُ عَنْهُ مَا أَصَابَ النَّاسُ مِنْ الدُّنْيَا فَقَالَ لَقَدْ رَأَيْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَظَلُّ الْيَوْمَ يَلْتَوِي مَا يَجِدُ دَقَلًا يَمْلَأُ بِهِ بَطْنَهُ‏.‏