Sayyiduna Abu Manfa'ah al-Hanafi (may Allah be pleased with him) said: I said: O Messenger of Allah, to whom should I show kindness? He (peace and blessings be upon him) said: "To your mother, your father, your sister, your brother, and your freed slave who comes after that. This is an obligatory right and a tie of kinship to be maintained."
Hadith Referenceالمعجم الكبير للطبراني / مسند من يعرف بالكنى / 18990