The Origins of the Islamic State/Part 9/Chapter 2
CHAPTER II
The Caliphate of ʿUmar ibn-al-Khaṭṭâb
Abu-ʿUbaid chief commander. When ʿUmar ibn-al-Khaṭṭâb was proclaimed caliph, he directed abu-ʿUbaid ibn-Masʿûd ibn-ʿAmr ibn-ʿUmair ibn-ʿAuf ibn-ʿUḳdah ibn-Ghiyarah ibn-ʿAuf ibn-Thaḳîf (who is identical with abu-l-Mukhtâr ibn-abi-ʿUbaid) to al-ʿIrâḳ with 1,000 men. Meanwhile, he wrote to al-Muthanna ibn-Ḥârithah, ordering him to receive abu-ʿUbaid and obey his word. In the company of abu-ʿUbaid, he sent Salîṭ ibn-Ḳais ibn-ʿAmr al-al-Anṣâri, saying to him, "Had it not been for the fact that thou art too hasty, I would have put thee in chief command. But warfare is a stubborn thing, and only the cautious man is fit for it."
Abu-ʿUbaid defeats Jâbân, al-Jâlînûs and other Persian chiefs. Abu-ʿUbaid marched forward and left no Arab tribe by which he passed without arousing its interest in the "holy war" and plunder. Thus, he was joined by a large host. On arriving in al-ʿUdhaib, he heard that Jâbân, the Persian, was at Tustar with a large body of men. Abu-ʿUbaid met Jâbân and put his troops to flight, taking some of them captive.
Thence abu-ʿUbaid proceeded to Durna[1] in which there was assembled a body of Persians. These abu-ʿUbaid chased to Kaskar. He then advanced to meet al-Jâlînûs,[2] who was at Bârûsma [or Mârûsma]; but ibn-al-Andarzʿazz[3] made terms with him, agreeing to pay four dirhams on every person, provided abu-ʿUbaid should keep his way.
Abu-ʿUbaid sent al-Muthanna to Zandaward,[4] and finding that its inhabitants had violated their covenant, al-Muthanna fought against them, won the victory and carried away [many] captives. Abu-ʿUbaid also sent ʿUrwah ibn-Zaid-al-Khail aṭ-Ṭâʾi to az-Zawâbi, with whose chief [dihḳân] me made terms similar to those made with Bârûsma.