Narrated Abdullah bin Dinar: 'Abdullah Bin 'Umar wrote to 'Abdul Malik bin Marwan, swearing allegiance to him: 'I swear allegiance to you in that I will listen and obey what is in accordance with the Laws of Allah and the Tradition of His Apostle as much as I can.'
— Sahih Bukhari, Volume 9, Book 92: Holding Fast to the Qur'an and Sunnah, Hadith #377