The Hadeeth of Abu Hurairah: That the Messenger of Allaah (sallallaahu alayhi wasallam) said:

The Angels take successions regarding you, the angels through the night and the angels through the day. They gather [at the time of] the Fajr prayr and the Asr prayer, then those who remained with you through the night
ascend up to Him and He asks them - and He is most-knowledgeable of them (his servants) - "How have you left my servants?" And they (the angels) say, "We came to them and they were praying, and we left them and they were praying".
The hadeeth is agreed upon (by both al-Bukhaaree and Muslim).
Source: "Mukhtasar al-Uluww" of Imaam adh-Dhahabee, p. 83.
Comment: This hadeeth is also a proof for the attribute of "kalaam" (speech) for Allaah, the Most High, since Allaah says to the Angels, "How have you left my servants?"