ʿEid al-Ghadīr is among important feasts and happy holidays of Shi’a held on Dhu l-Hijja 18; when according to reports, the noble Prophet (s) appointed Ali b. Abi Talib (a) as his caliph and the Imam after himself following an order from God. That event happened in the Prophet’s (s) Hajjat al-Wida’ (the Farewell Hajj), in 10/632 in a place called Ghadir Khumm