Musnad Ahmad 792:13

Yazid narrated to us, Bahz ibn Hakim ibn Mu'awiyah narrated to us, from his father, from his grandfather, who said: I said, "O Messenger of Allah, whom should I treat with goodness?" He said, "Your mother." I said, "Then who?" He said, "Then your mother." I said, "O Messenger of Allah, then who?" He said, "Your mother." I said, "Then who?" He said, "Then your father, then the nearest, then the nearest."