Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Noble Prophet (peace and blessings of Allah be upon him) said: "No son can repay the favors of his father, except that he finds his father as a slave, buys him, and sets him free (then he can fulfill his right)."
Hadith Referenceالادب المفرد / كتاب الوالدين / 10
Hadith Gradingالألبانی:صحیح
Hadith Takhrij«صحیح : أخرجه مسلم، العتق، باب فضل عتق الوالد: 1510 و أبوداؤد: 5138 و الترمذي: 1906 و ابن ماجه: 3659 ، الارواء : 1747»
Explanation & Benefits
Shaykh Maulana Usman Muneeb
Benefits and Issues: ➊ From this hadith, one can estimate the favor of parents—that no matter how much a person shows good conduct towards his parents, it is still insufficient, and it is not possible to repay the sacrifices of the parents. ➋ When an Islamic government engages in jihad, and during the war, any disbelievers who are captured are made slaves. In the early period of Islam, these people would often become Muslims after being influenced by the Muslims. Sometimes, the son would become free while the father remained a slave. In such a case, if the son purchases his father, the father becomes free automatically, but there is a great reward for the son. ➌ Shaykh al-Albani rahimahullah has written in Sahih al-Adab al-Mufrad, quoting Allamah al-Sindi, that even the breaths of a slave are not his own, and he is like a person on the verge of destruction, and granting him freedom is like giving him life. If a son grants freedom to his father, it is as if he has brought his father from non-existence into existence, and the father was also the cause of the son's coming into existence from non-existence. Therefore, this act of the son becomes equal to that of the father, so he has repaid the favor of the parent. And Allah knows best what is correct.
Source: Fadlullah al-Ahad: Urdu Commentary on al-Adab al-Mufrad, Page: 10