'Unrecognizable' in the Bible

It happened at the moment Ahijah heard the sound of her footsteps coming through the doorway, he said, "Come [in], wife of Jeroboam. Why [are] you making yourself unrecognizable? I have been sent a hard [message] for you:

"Whenever you fast, do not be sullen like the hypocrites, for they make their faces unrecognizable in order that they may be seen fasting by people. Truly I say to you, they have received their reward in full!