It is narrated from Sayyiduna Zayd bin Arqam (may Allah be pleased with him) that Sayyiduna Ali (may Allah be pleased with him) asked the people for testimony and said: I beseech by Allah the one who heard the Messenger of Allah (peace and blessings be upon him) say: O Allah! Whosoever I am his friend, Ali is also his friend. O Allah! Befriend whoever befriends Ali, and show enmity to whoever shows enmity to Ali. Upon hearing this, sixteen men stood up and testified (that indeed they had heard this hadith from the Messenger of Allah, peace and blessings be upon him).