The Battle of al-Madhār (1) took place in the month of Ṣafar that same year. It is also known as the Battle of al-Thani, after the river. Ibn Jarīr (2) relates that on that day the people said:

“Ṣafar of Ṣafars—in it every tyrant is slain at the meeting of the rivers.”

The cause of the encounter was that Hormuz (3) had written to Ardashīr and Shīrā informing them that Khalid was advancing toward him from al-Yamāmah. In reply, Kisrā sent reinforcements under a commander named Qārin (4) ibn Quriyāns. Qārin had not yet reached Hormuz when the affair between Hormuz and Khalid unfolded as already described, and some of the Persians fled. Qārin met the fugitives; they rallied around him, exhorted one another (5), and agreed to return against Khalid.

They moved to a place called al-Madhār, with Qubādh and Anūshjan (6) on Qārin’s right and left wings. When news reached Khalid, he distributed the four-fifths share of the booty from the Day of the Chains and dispatched the report to al-Ṣiddīq with al-Walīd ibn ʿUqbah. Khalid then advanced with his forces until he encamped at al-Madhār in full battle array. A desperate, furious fight ensued. Qārin stepped forward calling for single combat; Khalid came out to meet him, but the valiant chieftains hurried ahead. Maʿqil ibn al-Aʿshā ibn al-Nabbāsh (7) killed Qārin, ʿAdī ibn Ḥātim killed Qubādh, and ʿĀṣim killed Anūshjan. The Persians broke and ran; the Muslims charged after them, cutting them down from the rear, and on that day they killed thirty thousand, while many others drowned in the rivers and waterways.

Khalid remained at al-Madhār and handed each slayer his personal spoils—Qārin had stood at the pinnacle of Persian nobility. He then gathered the remaining booty, set aside one-fifth of it, and sent that share, together with the news of victory and glad tidings, to al-Ṣiddīq with Saʿīd ibn al-Nuʿmān of Banū ʿAdī ibn Kaʿb. Khalid stayed on until he had distributed the remaining four-fifths and took captive the families of the combatants who were present, sparing the peasants, whom he left under jizyah. Among the captives were Ḥabīb Abū al-Ḥasan al-Baṣrī, who was a Christian, Māfanna the freedman of ʿUthmān, and Abū Ziyād the freedman of al-Mughīrah ibn Shuʿbah.

Khalid appointed Saʿīd ibn al-Nuʿmān commander of the troops and Suwayd ibn Muqarrin overseer of the jizyah, ordering him to settle at al-Ḥufayr to collect the revenues, while Khalid himself remained to gather intelligence on the enemy.