Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 10
Narrated Abu Sufyan:
That Heraclius sent for him and said, "What did he, i.e. the Prophet order you?" I replied, "He orders us to offer prayers; to give alms; to be chaste; and to keep good relations with our relatives.