Musnad Abu Ya'la al-Mawsili 155:242

On the authority of Abu Hurayrah, he said: A man came to the Messenger of Allah, may Allah bless him and grant him peace, and said: "Who among the people is most deserving of my good companionship?" He said: "Your mother." He said: "Then who?" He said: "Then your mother." He said: "Then who?" He said: "Your mother." He said: "Then who?" He said: "Then your father."