When the Muslim forces reached unexpectedly at Muzayyah, it was night and the Persians and the Christian Arabs slept peacefully. Roaring masses of Muslim warriors hurled themselves on the Persian camp. So sudden was the Muslim attack that Persian army was unable to take any firm stand. There was confusion and panic in the ranks of the Persian army, and the Persians were slaughtered in thousands. The disaster that met the Persians at Muzayyah was more or less of the same order as they had suffered at Walaja. Helped by the darkness of the night many Persians and their auxiliaries found safety in withdrawing from the battlefield.

When the sun rose the following day, not a single Persian soldier could be seen at Muzayyah. Most of them lay dead at the battlefield, and the rest had found safety in flight. Among the Arabs who had lost their lives at Muzayyah were two persons, Abdullah and Labid who were Muslims and had certificates to that effect from Abu Bakr himself. Some of the critics of Khalid held him guilty of killing Muslims. Abu Bakr held that such things were likely to occur when Muslims chose to live in the midst of non-Muslims, against whom military operations were undertaken. Abu Bakr, however, paid blood money to the heirs of the two persons from the Muslim Baitul Mall.

Battle of Saniyy. The victory of the Muslims at Muzayyah exposed the Christian Arab pockets of Saniyy, Zumeil, and Ruzab to Muslim attack. Saniyy being close to Muzayyah become the first objective of the attack of the Muslim forces. From Muzayyah three Muslim columns marched through separate routes and arrived at Saniyy according to plan on pre-determined time and date. A three pronged attack was launched on the Christian Arab camp at Saniyy. The Christian Arabs were no match for the trained forces of Khalid and were slaughtered in thousands. The Christian Arab Commander Rabee a bin Bujeir was slain on the battlefield. Among the captives was the beautiful daughter of Rabee'a. She was sent to Madina, where Ali married her.

Battle of Zumeil. From Saniyy the Muslim forces marched to Zumeil. Here again a three pronged attack was launched by three columns according to a pre-determined plan. The Christian Arab forces at Zumeil met with disaster and were annihilated. The Muslims won considerable booty both at Saniyy and Zumeil.

Battle of Ruzeb. From Zumeil, the Muslim forces proceeded to Ruzab. Here Hilal the son of the Christian Arab chief Aqqa who had fallen at 'Ein-at-Tamr had collected a large force of the Christian Arabs to give a fight to the Muslims and avenge his father's death. When Hilal came to know of the fate of the Christian Arabs at Saniyy and Zumeil, he lost heart. When the Muslim forces arrived at Ruzab, there was no enemy to oppose them, and they occupied Ruzab without any resistance. Hilal and his forces withdrew before the arrival of the Muslims.

Muslim domination. With the completion of these operations, the entire region to the west of the Euphrates from Uballa to Anbar came under the complete domination of the Muslims; all pockets of the Persians of the Christian Arabs in this region were completely liquidated.