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: 6208
This hadith has been narrated on the authority of Zuhri with the same chain of transmitters with the addition of Ibn Uyaina (and the words are):" Do not cut off (mutual relations)."