Verses with the word mightest in the Old Testament (11 verses):

Deuteronomy 4:35
Unto thee it was shewed, that thou mightest know that the LORD he is God; there is none else beside him.

Deuteronomy 6:2
That thou mightest fear the LORD thy God, to keep all his statutes and his commandments, which I command thee, thou, and thy son, and thy son's son, all the days of thy life; and that thy days may be prolonged.

Judges 16:6
And Delilah said to Samson, Tell me, I pray thee, wherein thy great strength lieth, and wherewith thou mightest be bound to afflict thee.

Judges 16:10
And Delilah said unto Samson, Behold, thou hast mocked me, and told me lies: now tell me, I pray thee, wherewith thou mightest be bound.

Judges 16:13
And Delilah said unto Samson, Hitherto thou hast mocked me, and told me lies: tell me wherewith thou mightest be bound. And he said unto her, If thou weavest the seven locks of my head with the web.

1 Samuel 17:28
And Eliab his eldest brother heard when he spake unto the men; and Eliab's anger was kindled against David, and he said, Why camest thou down hither? and with whom hast thou left those few sheep in the wilderness? I know thy pride, and the naughtiness of thine heart; for thou art come down that thou mightest see the battle.

Nehemiah 9:29
And testifiedst against them, that thou mightest bring them again unto thy law: yet they dealt proudly, and hearkened not unto thy commandments, but sinned against thy judgments, (which if a man do, he shall live in them;) and withdrew the shoulder, and hardened their neck, and would not hear.

Psalms 8:2
Out of the mouth of babes and sucklings hast thou ordained strength because of thine enemies, that thou mightest still the enemy and the avenger.

Psalms 51:4
Against thee, thee only, have I sinned, and done this evil in thy sight: that thou mightest be justified when thou speakest, and be clear when thou judgest.

Proverbs 22:21
That I might make thee know the certainty of the words of truth; that thou mightest answer the words of truth to them that send unto thee?

Daniel 2:30
But as for me, this secret is not revealed to me for any wisdom that I have more than any living, but for their sakes that shall make known the interpretation to the king, and that thou mightest know the thoughts of thy heart.