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: 6225
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: Verily. Allah would say on the Day of Resurrection: Where are those who have mutual love for My Glory's sake? Today I shall shelter them in My shadow when there is no other shadow but the shadow of Mine.