Verse 61 of Sura 3 provides {3:61}: "And who so disputes with you concerning God after the knowledge which has come to you say to him: Come, we will summon our sons, your sons, our women and your women and ourselves and yourselves. Then we will pray humbly to our Lord, and solemnly invoke the curse of Allah upon those who lie."
This verse alludes to the deputation of the Christians of Najran who came to Madina to hold discussion with the Holy Prophet about the truth of Islam. In this verse, the reference to "Our sons, and our women" includes reference to Ali, Fatima, Hasan and Husain. Verse 3, Sara Verse 3 of Sura 9 provides: And a proclamation from God and His Apostle to the people on the day of 'Greater Pilgrimage' that Allah is free from obligation to the idolaters and so is His Messenger. So, if you repent it will be better for you; but if you are averse, then know that you cannot escape Allah. Give tidings O Muhammad of a painful doom to those who disbelieve". In pursuance of this verse, the Holy Prophet commissioned Ali to go to the 'Greater Pilgrimage' to announce the verses of the Sura of "Immunity" wherein God absolved the Muslims from all obligations under the treaties previously concluded with the idolaters.