'Be Strong' in the Bible

And, lo, Amariah the head priest is over you for every matter of Jehovah, and Zebadiah son of Ishmael, the leader of the house of Judah, is for every matter of the king, and officers the Levites are before you; be strong and do, and Jehovah is with the good.'

but if thou art going -- do it, be strong for battle, God doth cause thee to stumble before an enemy, for there is power in God to help, and to cause to stumble.'

Be strong and courageous, be not afraid, nor be cast down from the face of the king of Asshur, and from the face of all the multitude that is with him, for with us are more than with him.