Musnad Ahmad 27:1553

Hashim narrated to us, Abu Khaythama narrated to us, ‘Ata’ ibn al-Sa’ib narrated to us, from Kathir ibn Jumhan, who said: I said: "O Abu ‘Abd al-Rahman," — or someone else said it to him — "Why do I see you walking while the people are hastening?" He said: "If I walk, I have seen the Messenger of Allah, may Allah bless him and grant him peace, walk. And if I hasten, I have seen the Messenger of Allah, may Allah bless him and grant him peace, hasten. But I am an old man."