Good Manners and Form (Al-Adab)

Bukhari :: Book 8 :: Volume 73 :: Hadith 105

Narrated Anas:

When 'Abdur-Rahman came to us, the Prophet established a bond of brotherhood between him and Sa'd bin Ar-Rabi'. Once the Prophet said, "As you (O 'Abdur-Rahman) have married, give a wedding banquet even if with one sheep."