(6) بَابُ جَزَاءِ الْوَالِدَيْنِ
Abu Hurayra reported that the Prophet, may Allah bless him and granthim peace, said, "A child cannot repay his father unless he finds him asa slave and the buys him and sets him free."
Reference: Al-Adab Al-Mufrad 10
In-book reference: Book 1, Hadith 10
English translation: Book 1, Hadith 10