Musnad Ahmad 790:176

'Abd al-Wahhab ibn 'Ata narrated to us, Yunus informed us, from al-Hasan, from 'Imran ibn Husayn, that the Prophet, peace and blessings of Allah be upon him, was on a journey, and he slept through the dawn prayer until the sun rose. He awoke and gave an order, so the adhan was called. Then he prayed two rak'ahs. Then he waited until it (the sun) had risen high, then he gave an order, so he stood and prayed.