Pseudo-Chrysostom
Catena Aurea · Matthäusevangelium 6
But thou, when thou fastest, anoint thine head, and wash thy face; That thou appear not unto men to fast, but unto thy Father which is in secret: and thy Father, which seeth in secret, shall reward thee openly.
Spiritually interpreted—the face may be understood to mean the mental conscience. And as in the eyes of man a fair face has grace, so in the eyes of God a pure conscience has favour. This face the hypocrites, fasting on man’s account, disfigure, seeking thereby to cheat both God and man; for the conscience of the sinner is always wounded. If then you have cast out all wickedness from your heart, you have washed your conscience, and fast well.