Ibn ʿAbbās and others said:
“The faces of the people of the Sunnah and the mainstream community will be whitened, while the faces of the people of innovation and division will be blackened.”

The point is that whatever the heart contains—an intention of truthfulness, love, righteousness, and the like—may manifest itself on the face so clearly that it is grasped with immediate, self-evident certainty, one of the most obvious forms of necessary knowledge. The same applies to what the heart holds of an intention to lie, hatred, debauchery, and so forth. A man may travel with someone he has never met before that very hour, yet after watching him for a short time and listening to his words, he soon comes to know whether the person is trustworthy and can be relied upon, or not. At first he may be unsure and could even err, but the common experience is that the reality becomes clear to most people with time.

Likewise, a neighbor comes to know his neighbor, and a business partner comes to know the one with whom he deals.

For this reason, when a man testified in the presence of ʿUmar b. al-Khaṭṭāb and another vouched for him, ʿUmar asked:
“Are you his closest neighbor—do you know how he is in the evening and the morning?”
He replied, “No.”
ʿUmar said, “Have you dealt with him in the dirham and the dinar, by which people’s trustworthiness is put to the test?”
He answered, “No.”
ʿUmar asked, “Have you traveled with him on a journey that exposes people’s true character?”
He again replied, “No.”
ʿUmar then said, “Then you are—”