Abu Musa al-Ash'ari RA

Abu Musa al-Ash'ari RA was a Companion from the Yemeni tribe of the Ash'aris who later served as a governor under Umar RA. After Hunayn in 8 AH he avenged his uncle Abu Amir, who was killed in a skirmish, and brought his dying request for prayer to the Prophet ﷺ, who prayed for them both. Before Tabuk he asked the Prophet ﷺ for mounts for his tribe, and was given camels after first being refused. In 10 AH the Prophet ﷺ sent him to govern a province of Yemen alongside Mu'adh ibn Jabal RA. A governor's letter about undated orders, by one account his, helped prompt Umar RA to establish the Hijri calendar.