'Hereby' in the Bible

hereby ye shall be proved: by the life of Pharaoh ye shall not go forth hence, except your youngest brother come hither.

And the man, the lord of the land, said unto us, Hereby shall I know that ye are true men: leave one of your brethren with me, and take grain for the famine of your houses, and go your way;

And Moses said, Hereby ye shall know that Jehovah hath sent me to do all these works; for I have not done them of mine own mind.

And Joshua said, Hereby ye shall know that the living God is among you, and that he will without fail drive out from before you the Canaanite, and the Hittite, and the Hivite, and the Perizzite, and the Girgashite, and the Amorite, and the Jebusite.