Sahih Muslim
The Book of Virtue, Good Manners and Joining of the Ties of Relationship (Kitab Al-Birr was-Salat-I-wal-Adab)
Book Number: 032 / Hadith Number: 6200
Jubair b. Mut'im reported on the authority of his father that Allah's Messenger (may peace be upon him) said: The severer would not enter Paradise. Ibn Umar said that Sufyan (explained it as): One who severs the tie of kinship would not enter Paradise.