[1] He served with Sa'd ibn Abi Waqqas at the Battle of Qadisiyya against the Sassanid Persians, and then as a qadi at the Arab garrison town of Kufa until 641.
[2] In 642, he led the vanguard of Suraqa ibn Amr, who was charged with the conquest of the strategically located Persian fortress of Derbent.
[2] According to the History of the Prophets and Kings of al-Tabari, the Persian governor of Derbent, Shahrbaraz, offered to surrender the fortress to the Arabs and even to aid them against the unruly native Caucasian peoples, if he and his followers were relieved of the obligation to pay the jizya tax.
[3] Suraqa died soon after, and Abd al-Rahman remained in command at Derbent, which became an Arab base of operations against the powerful Khazar Khaganate to the north.
[1] After his death, the Khazars reportedly kept his body in a cauldron and venerated it, claiming that it could be used to bring rain or drought, and ensured victory in war.