Kulayb bin Manfa'ah narrates from his grandfather (may Allah be pleased with him) that he came to the Prophet (peace and blessings be upon him) and said: "O Messenger of Allah! Who is most deserving of kindness?" He (peace and blessings be upon him) said: "Your mother, your father, your sister, your brother, and your slave whose right is joined to yours, and with whom maintaining ties is obligatory."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7765