On standing up...
On standing up, al-Harith said: “O Allah, if what is uttered by Muhammad is true, send against us stones from the sky or bring us a painful doom.” Then he (PBUHH) said: By Allah, before reaching his camel, Allah pelted him with a stone from heaven, which fell upon the top of his head and went out from his posterior, causing his death. These verses were revealed by Allah the Almighty: “Demanded, a demander, the chastisement inevitable.
For, the disbelievers against it, there is no repelled.” This episode is reported by a large number of Ahl al-Sunnah scholars, other than those we referred to. Whoever desires to go through more references, can refer to the book al-Ghadir by al-Allamah al-Amini. Second Evidence It is related to the punishment of anyone concealing the witness regarding the incident of al-Ghadir which was inflicted by the imprecation uttered by Imam Ali (PBUH).
That was when Imam Ali, during a memorable day, rose up, and gathered people at al-Rahabah, proclaiming from over the minbar: I appeal to every Muslim who heard the Messenger of Allah (PBUHH), saying on the day of Ghadir Khumm.
“Ali is the master of whomever I am his master”, to stand up and give witness of what he heard, provided that he saw him by his own eyes and heard him by his own ears.” Thereat thirty , among whom sixteen Badrites (those who attended Battle of Badr), stood up and witnessed that he (PBUHH) took him by hand and addressed people, saying: “Do you know that I have more authority over the believers than they have over themselves? They said: Yes, you do.
He said: Of whomever, I am his master, this one (Ali) is also his master. O Allah, befriend whoever befriends him, and be the enemy of his enemy…” But jealousy and hatred harboured inside the hearts of some who attended the incident of al-Ghadir withheld them from standing and giving witness. Among them was Anas ibn Malik, toward whom Imam Ali descended the minbar (pulpit) and said to him: O Anas, what is the matter with you?
Why don’t you rise up together with the Messenger of Allah’s and give witness to what you heard on that day as they did? He replied: O Amir al-Muminin! I became old and forgot (that incident). Then Imam Ali said: If you are proven to be a liar, I invoke Allah to afflict you with leprosy in a way that no turban can cover.