يوم تبيض وجوه وتسود وجوه
On the Day when some faces will become white and some faces will become black;
on the Day of Resurrection.
This is when the faces of followers of the Sunnah and the Jama`ah will radiate with whiteness, and the faces of followers of Bid`ah (innovation) and division will be darkened, as has been reported from Ibn Abbas.
Allah said,
فٲما الذين اسودت وجوههم أكفرتم بعد إيمانكم
As for those whose faces will become black (to them will be said): "Did you reject faith after accepting it!"
Al-Hasan Al-Basri said,
"They are the hypocrites.''
فذوقوا العذاب بما كنتم تكفرون
Then taste the torment (in Hell) for rejecting faith.
and this description befits every disbeliever
وأما الذين ابيضت وجوههم ففي رحمة الله هم فيها خالدون