Al-Adab Al-Mufrad #150

Al-Hasan reported that Sa'sa'a ibn Mu'awiya told him that he met Abu Dharr finding him alone without any relatives and asked, "Don't you have any children, Abu Dharr?" He said, "I heard the Messenger of Allah, may Allah bless him and grant him peace, say, 'There is no Muslim who has three of his children die before they reach puberty without Allah admitting him to the Garden by virtue of His mercy to them. There is no man who frees a Muslim with Allah Almighty making each of the limbs of the one who is freed a ransom for each of the emancipator's limbs.'"