Is there a Prophetic Hadith reported about a midday nap (qaylulah), and does it have a specific time or duration? And is the Hadith "Take a nap, for indeed the devils do not take naps" authentic?

Qailulah is sleeping or resting at midday. Jurists have differed on its exact timing, whether it is before or after the sun's zenith (zawwal). The preponderant opinion is that it is after the zawwal, based on the hadith of Sahl ibn Sa'd. The qailulah nap is recommended by the majority of scholars, due to the Prophet (peace be upon him) saying: "Take a midday nap (qailulah), for the devils do not take midday naps," and because it strengthens one for acts of obedience and for night prayers (qiyam al-layl).