And whoever disputes with you concerning him after the knowledge that has come to you, say: “Come! Let us call our sons and your sons, our wives and your wives, our selves and your selves, then let us humbly pray and invoke God's curse upon those who lie.”
And whoever disputes with you concerning him means that “After you have sincerely proclaimed what you were told, and have come to know the truth of the knowledge We imparted to you in your heart, do not be reticent in challenging them to mutual cursing. Trust that you have the force (qahr) and help (nuṣra), and that We are protecting you and have sheltered you in the wing of Our nearness.” If they had sought this mutual cursing, the valley would have rained fire down upon them, but God (سبحانه) gave them respite because He knew of the believers [yet to come] of their progeny.
This verse alludes to those whose states are no longer those of the sincere (ṣiddīqūn). When the lights [of the sincere] appear, what remains in [the others] fades away completely.