Narrated Anas: The Prophet (ﷺ) said, "If anyone of you feels drowsy while praying, he should sleep till he understands what he is saying (reciting)"
Book 4 · Hadith 79
صحيح البخاري
Narrated Anas: The Prophet (ﷺ) said, "If anyone of you feels drowsy while praying, he should sleep till he understands what he is saying (reciting)"