Musnad Ahmad 27:808

Waki’ narrated to us, from his father, from ‘Ata’ ibn al-Sa’ib, from Kathir ibn Jumhan, from Ibn ‘Umar, who said: "If I hasten, it is because I saw the Messenger of Allah, may Allah bless him and grant him peace, hasten; and if I walk, it is because I saw the Messenger of Allah, may Allah bless him and grant him peace, walk. And I am an old man."