Volume 4, Book 55, Number 631:
Narrated Abdullah bin Amr:
Allah’s Apostle said to me, “The most beloved fasting to Allah was the fasting of (the Prophet) David
who used to fast on alternate days. And the most beloved prayer to Allah was the prayer of David
who used to sleep for (the first) half of the night and pray for 1/3 of it and (again) sleep for a sixth of
it.”
Volume 4 – 796 / 1700
SAHIH BUKHARI VOLUME 4 > BOOK 55: PROPHETS