Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 17
Narrated Abu Huraira:
The Prophet said, "The word 'Ar-Rahm (womb) derives its name from Ar-Rahman (i.e., one of the names of Allah) and Allah said: 'I will keep good relation with the one who will keep good relation with you, (womb i.e. Kith and Kin) and sever the relation with him who will sever the relation with you, (womb, i.e. Kith and Kin).