because it is the curve by which one faces another, and this is the better view.

…to the lower extent of the jawbones and chin lengthwise, and from ear to ear widthwise; and he washes the fine hair upon it, and the outer surface of thick hair…

His statement, “to the lower extent of the jawbones and chin lengthwise”: the chin is where the two jawbones meet. The two jawbones are the bones in which the teeth are set.

Thus, whatever extends down from the jawbones must be washed. Likewise, if there is long hair on the chin, it must be washed, because the face is that by which one faces another, and one faces another by means of this hair; washing it is therefore obligatory.

Some scholars said that hair extending beyond the obligatory area need not be washed, because Allah says, “your faces” [al-Ma'idah 5:6], and hair is regarded as detached.

Ibn Rajab mentioned this in al-Qawa'id and held that whatever hangs down from the jawbones and chin need not be washed to be the sounder view. (1)

But the more cautious and preferable course is to wash whatever hangs down from the jawbones and chin.

His statement, “and from ear to ear widthwise”: the bare area between the sideburn and the ear is part of the face.

The hair above the protruding bone belongs to the head. This is the boundary of the face.

The evidence that it must be washed is the statement of Allah, Most High: “O you who believe! When you rise to pray, wash your faces…” [al-Ma'idah 5:6].

His statement, “and the fine hair upon it, and the outer surface of thick hair”: fine hair is: