Prophet Hārūn ﷺ (Aaron) was the elder brother of Mūsā ﷺ and was appointed as his minister and co-prophet at Mūsā's ﷺ own request. Mūsā ﷺ asked Allah: "And appoint for me a minister from my family — Hārūn, my brother." He was renowned for his eloquence and gentle manner.
When Mūsā ﷺ went to Mount Sinai for 40 nights, he left Hārūn ﷺ in charge of the Israelites. During this period, a man named Al-Sāmirī fashioned a golden calf and led the people into idol worship. Hārūn ﷺ tried his utmost to stop them but was outnumbered and physically restrained. When Mūsā ﷺ returned enraged, Hārūn ﷺ explained his helplessness with humility.