It is narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "The ties of kinship are suspended from the Throne of the Most Merciful. The one who merely repays in kind is not the (true) joiner of kinship; rather, the joiner of kinship is he who, when the tie with him is broken, restores the tie."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الصدقات / 13220