SALMAN AL-FARISI took part in Sayyiduna ‘Umar’s Persian campaign and played a crucial role in the conquest of Mada’in (“al-Bidayah wan-Nihayah” vol. 5 pp. 135-140). He had also acted as governor of Mada’in for Sayyiduna ‘Umar (“al-Isabah” vol. 3 p. 113)
In shiite book, Tuhfa Abbasi we read
Salman was appointed a the governor of Mada’in during the caliphate of ‘Umar ibn Khattab and remained in that position until his death.
Mohammad Hassan Faghfoory, Najīb al-Dīn Riḍā Tabrīzī – Page 30
Mulla Baqir Majlisi also writes in his book that Salman Farsi acted as governor of Umar Farooq in Madain, which was the capital of Iran at that time.
Similarly we read in Talkhees al-Shafi
تولى سلمان لعمر المدائن
Salman acted as governor for Umar in Madain
Talkhees al-Shafi , p. 402