Matthew 6:16-18 - The Sermon On The Mount: How To Fast
16 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. 17 But thou when thou fastest, anoint thy head, and wash thy face. 18 That thou appear not unto men to fast, but to thy Father who is in secret, and thy Father who seeth in secret shall reward thee openly.