After his speech, the Messenger of Allah (peace be upon him and his household) asked everybody to give the oath of allegiance to Ali(A.S.) and congratulate him. Among those who did so was 'Umar b. al-Khattab, who said: "Well done Ibn Abi Talib! Today you became the Leader (mawla) of all believing men and women."
Number of People in Ghadir Khumm
Allah ordered His Prophet (peace be upon him and his household) to inform the people of this designation at a time of crowded populous so that all could become the narrators of the tradition, while they exceeded a hundred thousand. Narrated by Zayd b. Arqam: Abu al-Tufayl said: "I heard it from the Messenger of Allah (peace be upon him and his household), and there was no one (there) except that he saw him with his eyes and heard him with his ears."