'Fail' in the Bible

David said to Saul, "Let no man's heart fail because of him. Your servant will go and fight with this Philistine."

David said to Jonathan, "Behold, tomorrow is the new moon, and I should not fail to dine with the king; but let me go, that I may hide myself in the field to the third day at evening.

David inquired of Yahweh, saying, "If I pursue after this troop, shall I overtake them?" He answered him, "Pursue; for you shall surely overtake them, and shall without fail recover all."