'Lose Heart' in the Bible

The LORD then told Joshua, "Don't be afraid or lose heart! Take all the fighting men with you, and go up right now to Ai. Take note that I have handed over the king of Ai into your control, along with his people, his city, and his land.

Tell him, "Be careful, be calm, don't be afraid, and don't lose heart because of these two smoldering stumps of torches, that is, because of the fierce anger of Rezin, from Aram, and Remaliah's son.