Musannaf Ibn Abi Shayba 3:1141

Waki’ narrated to us, from Shu’bah, from Hamzah al-Dabbi, who said: I heard Anas saying: "When the Prophet of Allah (may Allah bless him and grant him peace) would descend at a stopping place, he would not depart until he had prayed Dhuhr." Muhammad ibn ‘Amr said to him: "Even if it were the middle of the day?"