What was the pledge given by Abdullah bin Umar when the people took an oath of allegiance to Abdul Malik?
 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."