Matthew 6:16–18 (KJV) — “Moreover when ye fast, be not, as the hypocrites, of a sad countenance: for they disfigure their faces, that they may appear unto men to fast. Verily I say unto you, They have their reward. 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.”
Isaiah 58:6 (KJV) — “Is not this the fast that I have chosen? to loose the bands of wickedness, to undo the heavy burdens, and to let the oppressed go free, and that ye break every yoke?”
Joel 2:12 (KJV) — “Therefore also now, saith the LORD, turn ye even to me with all your heart, and with fasting, and with weeping, and with mourning.”