The Messenger of Allah ﷺ said, "A child cannot repay his father, unless he finds him as a slave and buys him and sets him free."
حدثنا وكيع قال حدثنا سفيان عن سهيل بن أبي صالح عن أبيه
قال رسول الله ﷺ لا يجزي ولد والده إلا أن يجده مملوكا فيشتريه فيعتقه
Its isnad is sahih. Muslim narrated it, 2/1148, no. 1510, in the book of manumission, chapter on the merit of freeing one's father, Tirmidhi 4/315, no. 1906, Abu Dawud 4/335, no. 5137, Ibn Majah 2/1207, no. 3659, and Tayalisi, 337, no. 2583 of Minhah.