When the Messenger of Allah was coming back from the battle of Khaibar, night came and he felt sleepy, so he made camp and said to Bilal: "Keep watch for us tonight." Bilal prayed as much as Allah decreed for him, and the Messenger of Allah and his Companions went to sleep. When dawn was approaching, Bilal went to his mount, facing towards the east, watching for the dawn. Then Bilal's eyes grew heavy while he was leaning on his mount (and he slept). Neither Bilal nor any of his Companions woke until they felt the heat of the sun. The Messenger of Allah was the first one to wake up. The Messenger of Allah was startled and said: "O Bilal!" Bilal said: "The same thing happened to me as happened to you. May my father and mother be ransomed for you, O Messenger of Allah!" He said: "Bring your mounts forward a little." So they brought their mounts forward a little (away from that place). Then the Messenger of Allah performed ablution and told Bilal to call the Iqamah for prayer, and he led them in the prayer. When the Prophet finished praying, he said: "Whoever forgets a Salah, let him pray it when he remembers, for Allah says: And perform the prayer for My remembrance." [Ta-Ha: 14] He (one of the narrators) said: "Ibn Shihab used to recite this Verse as meaning, 'when you remember'."