Sunan Abi Dawud Book 2, Hadith 53
The Messenger of Allah (ﷺ) was on his journey. They (the people) slept abandoning the Fajr prayer. They awoke by the heat of the sun. Then they travelled a little until the sun rose high. He (the Prophet) commanded the mu'adhdhin (one who called for prayer) to call for prayer. He then offered two rak'ahs of prayer (sunnah prayer) before the (obligatory) fajr prayer. Then he (the mu'adhdhin) announced for saying the prayer in congregation (i.e. he uttered iqamah). Then he led them in the morning prayer.
If any one forgets a prayer or oversleeps, he should observe it when he remembers it ; there is no expiation for it except that.
We were in the company of the Messenger of Allah (ﷺ) during one of his journeys. He overslept abandoning the morning prayer until the sun had arisen. The Messenger of Allah (ﷺ) awoke and said: Go away from this place.
He then commanded Bilal to call for prayer. He called for prayer. They (the people) performed ablution and offered two rak'ahs of the morning prayer (sunnah prayer). He then commanded Bilal (to utter the iqamah, i.e. to summon the people to attend the prayer). He announced the prayer (i.e. uttered the iqamah) and he led them in the morning prayer.