Verses with the word couldest in the Old Testament (3 verses):
Will he reserve his anger for ever? will he keep it to the end? Behold, thou hast spoken and done evil things as thou couldest.
Thou hast played the whore also with the Assyrians, because thou wast unsatiable; yea, thou hast played the harlot with them, and yet couldest not be satisfied.
The king answered unto Daniel, and said, Of a truth it is, that your God is a God of gods, and a Lord of kings, and a revealer of secrets, seeing thou couldest reveal this secret.