Hadithcore
Sahih al-Bukhari, 4562
sahih

Narrated Abu Talha:

Slumber overtook us during the battle of Uhud while we were in the front files. My sword would fall from my hand and I would pick it up, and again it would fall down and I would pick it up again.

حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ بْنِ عَبْدِ الرَّحْمَنِ أَبُو يَعْقُوبَ، حَدَّثَنَا حُسَيْنُ بْنُ مُحَمَّدٍ، حَدَّثَنَا شَيْبَانُ، عَنْ قَتَادَةَ، حَدَّثَنَا أَنَسٌ، أَنَّ أَبَا طَلْحَةَ، قَالَ غَشِيَنَا النُّعَاسُ وَنَحْنُ فِي مَصَافِّنَا يَوْمَ أُحُدٍ ـ قَالَ ـ فَجَعَلَ سَيْفِي يَسْقُطُ مِنْ يَدِي وَآخُذُهُ، وَيَسْقُطُ وَآخُذُهُ‏.‏

References2 variants
In-Book Reference
Book 65, Hadith 84
USC-MSA web (English) reference
Vol. 6, Book 60, Hadith 85 (deprecated numbering scheme)