He played a role in the construction of the Dome of the Rock in Jerusalem in the early part of his father Caliph Abd al-Malik's reign (r. 685–705).
[6] Sa'id was appointed governor of Mosul by Abd al-Malik,[7] who conquered Iraq from the Umayyads' opponents, the Zubayrids, in 691.
The 8th-century historian al-Waqidi attributes to him the construction of city walls, but these were later torn down by the Abbasid caliph Harun al-Rashid in 796.
[9] Sa'id is further credited in medieval Muslim sources for constructing a mosque, a monastery, a market, and the pavement of Mosul's streets.
[3] He commanded the left flank of the Umayyad army during the summer expedition of 724, but his forces incurred heavy losses.
[16] In excavations carried out by an Israeli archaeological team in Beit Shean in 1990, a broken bronze weight produced on the orders of Sa'id was unearthed.
[16] In addition to the Muslim statement of belief, the surviving portion of the rare weight bore an inscription in Kufic Arabic that read: "Ordered by the Amir Sa'id ibn Abd al-Malik at the hands of ...".
Al-Asbagh married a sister of Abd al-Rahman I and their descendants held high-ranking positions as qadis (judges) and commanders.