Rubuta ci gaba ga wannan sakin layi - Gwamnan Kufa, Ammar ibn Yasir, ya sami bayanan sirri na ƙungiyoyin Farisa da taro a Nahavand kuma ya ba da rahoto ga Umar. Kodayake Umar ya nuna sha'awar Mesopotamiya ta zama iyakar gabashinsa, yawan sojojin Farisa a Nahavand ya tilasta masa yin aiki. Yanzu ya gaskata cewa muddin Farisa ta kasance a ƙarƙashin sarautar Sassanid, za a ci gaba da kai wa Mesopotamiya hari. An nada Hudheifa ibn Al Yaman a matsayin kwamandan sojojin Kufa, kuma an umurce shi da ya yi tafiya zuwa Nahavand. Abu Musa ya yi tafiya zuwa Nahavand daga Busra, yayin da Nouman ibn Muqarrin ya yi tafiya daga Ctesiphon. Umar ya yanke shawarar da kansa ya dauki sojojin da aka tattara a Madina zuwa Nahavand don karɓar cikakken umurni. Membobin Majlis al Shura, duk da haka, sun ba da shawarar cewa Umar ya kamata ya jagoranci kamfen daga Madina, ya nada wani kwamandan filin wasa mai basira don Nahavand. Umar ya yarda, ya nada Mugheera ibn Shuba a matsayin kwamandan sojojin da aka tattara a Madina, da Nouman ibn Muqarrin a matsayin babban kwamandan a Nahavand. Sojojin musulmi sun fara tattarawa a Tazar, sannan suka kayar da Farisawa a yakin Nahavand
a cikin Disamba 642. Nouman ya mutu a cikin aikin, kuma, bisa ga umarnin Umar, Hudheifa ibn Al Yaman ya zama sabon babban kwamandan. Bayan haka, Musulmai sun kama duk gundumar Hamadan, suna fuskantar juriya mai rauni.