Musnad Ahmad 701:1

Qutaybah ibn Sa'id narrated to us—and Qutaybah wrote it to me—Mujammi' ibn Ya'qub narrated to us, from Muhammad ibn Isma'il ibn Mujammi', who said: It was said to 'Abdullah ibn Abi Habibah: "What did you reach of the Messenger of Allah (may Allah bless him and grant him peace)?" And the Messenger of Allah (may Allah bless him and grant him peace) had arrived while he was a young boy. He said: "The Messenger of Allah (may Allah bless him and grant him peace) came to us one day to our mosque—meaning the mosque of Quba." He said: "So we came and sat with him, and the people sat with him." He said: "He sat for as long as Allah willed that he sit, then he stood to pray, and I saw him praying in his sandals."