Abu Talha reported,

I raised my head on the day of Uhud and began to look around, and there was not a single one of them that day who was not swaying beneath his shield from drowsiness. That is what is referred to in His statement عز وجل, "Then He sent down upon you, after the distress, security in the form of drowsiness" [Aal Imran 3:154].

Azami 12099

Sahih

عن أبي طلحة قال

رفعت رأسي يوم أحد فجعلت أنظر، وما منهم يومئذ أحد إلا يميد تحت جحفته من النعاس، فذلك قوله عز وجل: {ثم أنزل عليكم من بعد الغم أمنة نعاسا}.

الأعظمي 12099صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Tafsir of the great Quran
Chapter
Virtues of Surah Baqarah
Section
His saying, "Then He sent down upon you, after the distress, security in the form of drowsiness overcoming a group of you, while another group was concerned only about themselves, thinking about Allah other than the truth, the thought of ignorance. They say, 'Is there anything for us in this matter?' Say, 'Indeed, the matter belongs entirely to Allah.' They conceal within themselves what they do not reveal to you. They say, 'If we had any say in the matter, we would not have been killed here.' Say, 'Even if you had been in your houses, those decreed to be killed would have gone forth to their places of death, so that Allah might test what is in your breasts and purify what is in your hearts. And Allah"
Numbering
Jami al-Kamil 12099 (2nd edition)
Azami 12099