Bukhari

Hadith Commentary:
(1)
The meal after midday is called "ghada" and sleeping at that time is called "qaylulah" (siesta). It was the custom of the Arabs that after eating the midday meal, they would take a qaylulah. Doing so makes one’s disposition lively and light.

(2)
Qaylulah is a Sunnah practice. The Messenger of Allah sallallahu alayhi wa sallam said: "You should do qaylulah, for the devils do not do qaylulah." There is some discussion regarding the chain of narration of this report, but the preferred opinion is that this hadith is reliable. (Silsilat al-Ahadith al-Sahihah by al-Albani, Hadith: 1647) Likewise, the statement of Khawat ibn Jubayr radi Allahu anhu is transmitted with a sound chain: sleeping in the early part of the day causes irritation, sleeping at midday is conducive to health, and sleeping in the last part of the day is a sign of foolishness. (Fath al-Bari: 11/84)