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: 6354
'A'isha reported Allah's Messenger (may peace be upon him) as saying: Gabriel impressed upon me (kind treatment) towards the neighbour (so much) that I thought as if he would confer upon him the (right) of inheritance.