Sahih Adab al-Mufrad

856/1119 (Authentic chain of narration) From Abdullah ibn Dinar; that Abdullah ibn Umar wrote to Abd al-Malik ibn Marwan pledging allegiance to him, so he wrote to him: In the name of Allah, the Most Gracious, the Most Merciful, to Abd al-Malik, Commander of the Faithful, from Abdullah ibn Umar: Peace be upon you; indeed, I praise Allah to you, there is no deity except Him, and I acknowledge to you hearing and obedience according to the Sunnah of Allah and the Sunnah of His Messenger, as much as I am able.