'Fail' in the Bible

David said to Saul, “Let no man’s courage fail because of him (Goliath). Your servant will go out and fight with this Philistine.”

David said to Jonathan, “Behold, tomorrow is the New Moon [observance], and I should sit at the table to eat [the sacrificial meal] with the king; but let me go, so that I may hide myself in the field until the third evening.

David inquired of the Lord, saying, “Shall I pursue this band [of raiders]? Will I overtake them?” And He answered him, “Pursue, for you will certainly overtake them, and you will certainly rescue [the captives].”