Chapter 34: Etiquette
Abu Hurairah, may Allah be pleased with them, said that: Allah' s Messenger said: "They said: 'O Messenger of Allah, whom should I treat kindly?' He said: 'Your mother.' He said: 'Then who?' He said: 'Your mother." He said: 'Then who?' He said: 'Your father'. He said: 'Then who?' He said: 'The next closest and the next closest.'"
Sunan Ibn Majah 3658