G2480–ἰσχύω–ischuō

For a testament has effect after death; for what power has it while the man who made it is living?

ἰσχύει ischuei “it is in force”

So then, make a statement of your sins to one another, and say prayers for one another so that you may be made well. The prayer of a good man is full of power in its working.

ἰσχύει ischuei “prevails”

And they were overcome, and there was no more place for them in heaven.

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