'Fail' in the Bible

The only one I will not cut off from my altar [is you]. [Rather], to cause your eyes to fail and to cause your soul to grieve, {all the members of your household} will die [as] men.

David said to Saul, "Do not let anyone's heart fail concerning him! Your servant will go and fight with this Philistine."

{So may Yahweh punish Jonathan and more} if {my father decides to do you harm} and if {I fail to disclose it to you} and send word to you that you can go safely. And may Yahweh be with you, as he has been with my father.