صحيح البخاري

Narrated `Abdullah bin Dinar:

When the people took the oath of allegiance to `Abdul Malik, `Abdullah bin `Umar wrote to him: "To Allah's Slave, `Abdul Malik, Chief of the believers, I give the Pledge of allegiance that I will listen to and obey Allah's Slave, `Abdul Malik, Chief of the believers, according to Allah's Laws and the Traditions of His Apostle in whatever is within my ability; and my sons too, give the same pledge."