(38) بَابُ أَحَبُّ الصَّلاَةِ إِلَى اللَّهِ صَلاَةُ دَاوُدَ
Narrated `Abdullah bin `Amr:
Allah's Messenger (ﷺ) 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."
Reference: Sahih al-Bukhari 3420
In-book reference: Book 60, Hadith 92
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 55, Hadith 631