Bahz bin Hakim (RA) narrated from his father, from his grandfather who said: "I said: 'O Messenger of Allah! Who most deserves (my) reverence?' He (SAW) said: 'Your mother.'" He said: "I said: 'Then who?' He said: 'Your mother.'" He said: "I said: 'Then who?' He said: 'Your mother.'" He said: "I said: 'Then who?' He said: 'Then your father, then the nearest relatives, then the nearest relatives.'"
(Jami` at-Tirmidhi 1897, Book 27, Hadith 1)
(Jami` at-Tirmidhi 1897, Book 27, Hadith 1)