Commission of Khalid bin Walid. It was at this critical juncture that Abu Bakr commissioned Khalid bin Walid to undertake operations against Musailma. Elaborate arrangements were made to reinforce the army of Khalid. Seasoned soldiers were included in the force under his command. Bar'a bin Malik and Thabit bin Qais led the contingents of the Ansar, while Abu Khadhifa bin Utba and Zaid bin Khattab led the contingent of the Muhajreen. Against his declared policy, Abu Bakr permitted the veterans of Badr to join the forces of Khalid. Among others, those who joined the force included: Abdur Rahman son of Abu Bakr; Abdullah son of Umar; Abu Dujana the renowned warrior of Uhud; and Manwiyiah who later founded the Umayyad rule.

From Madina the Muslim army proceeded to Butaha. Here contingents from the Muslim tribes joined the force. From there the Muslim army marched south to Yamama valley under the command of Khalid bin Walid. In the way the Muslim army came across some men of Banu Hanifa led by Maja'a bin Murrah. All of them except Maja'a were put to death under the orders of Khalid. Maja'a was kept in custody to serve as a hostage. He was put in chains, and entrusted to the custody of Laila, the new wife of Khalid who accompanied him to the battlefield.

The battle of Aqraba. Musailma intercepted the advance of the Muslim army at the plain of Aqraba. Here the two opposing armies arranged their ranks for the battle. The battle that followed was hotly contested. The forces of Musailma numbered over forty thousand, while the strength of the Muslim army did not exceed fifteen thousand. Besides being outnumbered the Muslim forces suffered from certain disabilities. There were differences between the tribes, the Ansar and the Muhajreen. A dust storm blew across the valley against the faces of the Muslims. Taking advantage of this the forces of Musailma increased their pressure, and the Muslims had to fall back. Some men of the Banu Hanifa even reached the tent of Khalid where Maja'a was in chains guarded by Laila. These men wanted to kill Laila, and rescue Maja'a. Maja'a called upon them to desist from raising their hands against a woman. He wanted them to go and kill some men. These men left the camp, and said that they would return after some time to rescue Maj a'a. In the confusion that followed the party could not come back, and in the meantime the Muslims were able to take precautionary measures.

When the battle for the first day ended there was jubilation in the camp of Musailma. Though Khalid had been forced to withdraw he refused to admit defeat. He regrouped his army in tribal commands and exhorted the various tribes to show their valor on the battlefield. From within the Makkah and Madinite horsemen he created a reserve force of a thousand cavalrymen and kept them under his personal command.