What is the meaning of "a day when some faces will turn white and some faces will turn black," and does it refer to the appearance of the deceased at the time of death or to the appearance of a person on the Day of Resurrection?

The time when the faces of the believers will become white and the faces of the disbelievers will become black is the Day of Resurrection, as stated in the exegesis of the noble verse "On the Day when some faces will turn white and some faces will turn black," by Ibn Kathir, Al-Qurtubi, and others.