And the most beloved fast is the fast of Dawud (peace be upon him). He used to sleep in the (initial) half of the night and worship during one third of the night. Then, when one sixth of the night remained, he would sleep. Similarly, he used to fast one day and not fast the next day. Ali (may Allah be pleased with him) said that Aisha (may Allah be pleased with her) also said regarding this that whenever the Prophet (peace and blessings of Allah be upon him) was with me at the time of suhoor, he would be sleeping.

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."