The Rock of Israel - The Fountain whence Israel was derived.
He that ruleth over men must be just - More literally, מושל באדם צדיק moshel baadam tsaddik, He that ruleth in man is the just one; or, The just one is the ruler among men.
Ruling in the fear of God - It is by God’s fear that Jesus Christ rules the hearts of all his followers; and he who has not the fear of God before his eyes, can never be a Christian.