Till You Know What You’re Saying (Hadith No. 212)

Salam,
Bismillah.

Volume 1, Book 4, Number 212:

Narrated Anas:

The Prophet said, “If anyone of you feels drowsy while praying, he should sleep till he understands what he is saying (reciting).”

Reference: Hadith No. 211

But this obviously doesn’t mean that you can keep sleeping at Fajr time if you’re drowsy. :)

Wassalam.