'Abdullah ibn 'Amr reported: "The Prophet, may Allah bless him and grant him peace, said, 'A person who maintains ties of kinship is not someone who only does so with those who maintain ties with him. A person who maintains ties of kinship is someone who restores them when they have been cut off.'"

Riyadh-as-Saliheen by Imam Al-Nawawi, volume 3, hadith number 322 - Sunni Hadith