Some Sunni commentators further report that the first three verses of the chapter of al-Ma'arij (70:1-3) were revealed when a dispute arose after the Prophet [s] reached Madinah. It is recorded that:
On the day of Ghadir the Messenger of Allah summoned the people toward 'Ali and said: "Ali is the mawla of whom I am mawla." The news spread quickly all over urban and rural areas. When Harith Ibn Nu'man al-Fahri (or Nadhr Ibn Harith according to another tradition) came to know of it, he rode his camel and came to Madinah and went to the Messenger of Allah [s] and said to him: "You commanded us to testify that there is no deity but Allah and that you are the Messenger of Allah. We obeyed you. You ordered us to perform the prayers five times a day and we obeyed. You ordered us to observe fasts during the month of Ramadhan and we obeyed. Then you commanded us to offer pilgrimage to Makkah and we obeyed. But you are not satisfied with all this and you raised your cousin by your hand and imposed him upon us as our master by saying `Ali is the mawla of whom I am mawla.' Is this imposition from Allah or from you?"
The Prophet [s] said : "By Allah who is the only deity! This is from Allah, the Mighty and the Glorious."
On hearing this Harith turned back and proceeded towards his she-camel saying: "O Allah! If what Muhammad said is correct then fling on us a stone from the sky and subject us to severe pain and torture." He had not reached his she-camel when Allah, who is above all defects, flung at him a stone which struck him on his head, penetrated his body and passed out through his lower body and left him dead. It was on this occasion that Allah, the exalted, caused to descend the following verses:
"A questioner questioned about the punishment to fall. For the disbelievers there is nothing to avert it, from Allah the Lord of the Ascent." (70:1-3)
source : http://www.al-islam.org
