Sayyiduna Anas (may Allah be pleased with him) narrates this saying of the Prophet (peace and blessings be upon him): "Indeed the womb is a branch that holds on to the Throne. It will speak with an eloquent tongue and say: 'O Allah, join whoever joined me, and cut off whoever cut me off.' Then Allah Almighty will say: 'I am the Most Merciful, the Most Compassionate, and I have given the womb (that is, kinship) a name connected to My name. Whoever joins it, I will join him, and whoever cuts it to pieces, I will cut him off.'"
Al-Bazzar recorded it, and its chain is hasan (good).