G2480–ἰσχύω–ischuō

For a testament is of force where there hath been death: for it doth never avail while he that made it liveth.

ἰσχύει ischuei “it is in force”

Confess therefore your sins one to another, and pray one for another, that ye may be healed. The supplication of a righteous man availeth much in its working.

ἰσχύει ischuei “prevails”

And they prevailed not, neither was their place found any more in heaven.

ἴσχυσεν, ischusen “he had [enough] strength,”