'Abdullah bin 'Amr (May Allah be pleased with them) reported:
The Messenger of Allah (ﷺ) said, "The Salat which is dearest to Allah is that of (Prophet) Dawud; and As-Saum (the fasting) which is dearest to Allah is that of (Prophet) Dawud. He used to sleep half the night, get up to perform Salat for one-third of it, then sleep through the remaining one-sixth of it; and he used to observe Saum on alternative days."[Al-Bukhari and Muslim].
App reference: Book 9, Hadith 187
Arabic/English book reference: Book 9, Hadith 1177