Musnad Ahmad 431:3

'Abd al-Razzaq narrated to us, from Ma'mar, from al-Zuhri, who said: 'Abd al-Rahman ibn al-Azhar used to narrate that Khalid ibn al-Walid ibn al-Mughirah was wounded on that day, and he was in charge of the cavalry: the cavalry of the Messenger of Allah (may Allah bless him and grant him peace). Ibn al-Azhar said: I saw the Messenger of Allah (may Allah bless him and grant him peace) after Allah had defeated the disbelievers and the Muslims had returned to their camps, walking among the Muslims and saying: "Who will guide me to the camp of Khalid ibn al-Walid?" He said: So I walked—or he said: I hurried—in front of him, and I had reached the age of puberty, saying: "Who will guide me to the camp of Khalid?" until we arrived at his camp. Khalid ibn al-Walid was leaning against the rear of his saddle. The Messenger of Allah (may Allah bless him and grant him peace) came to him and looked at his wound. Al-Zuhri said: And I believe he said: "And the Messenger of Allah (may Allah bless him and grant him peace) blew upon it."