Musnad Abu Ya'la al-Mawsili 148:74

Abu Bakr ibn Abi Shaybah narrated to us, Waki' narrated to us, from Shu'bah, from Hamzah al-Dabbi, who said: I heard Anas saying: When the Messenger of Allah (peace and blessings of Allah be upon him) would descend at a stopping place, he would not depart until he had prayed the Dhuhr prayer. He said: So Muhammad ibn 'Amr said to him, "Even if it were at midday?" He said, "Even if it were at midday."