Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) said that when the Messenger of Allah (peace and blessings be upon him) set out for the expedition of Tabuk, he travelled through the night until it was the time before dawn (sahar). Then he made camp before dawn and said: "O Bilal, keep watch over the prayer for us." Bilal said: Yes, O Messenger of Allah. But sleep overcame Bilal and he fell asleep, and then they all slept until the sun distressed them. The Messenger of Allah (peace and blessings be upon him) got up and performed tayammum, then said to Bilal: "Give the adhan and the iqamah." Bilal said: Now? He (peace and blessings be upon him) said: "Yes." So they prayed after morning had come.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13699