“Fear God, my son, and the king,” that is, fear Christ, the true God and king. Or by “king” [Solomon] means the one who, before ruling over others, rules himself. “Do not be disobedient to any of them.” Indeed, the one who denies respect to the king elected by God dishonors God. The impious will be immediately punished: certainly nobody knows that hour or day. Often for those still living an unexpected punishment is taken. Therefore only the judge knows the opportunity and reason of the punishment to be inflicted, or somebody who is a very close friend. So never have a friend except for the Lord and the king: certainly if they are not friends of the Lord and the king, they are their enemies. In truth, do not consider as friends those who are not the friends of the king and the Lord.
Fear the Lord, my son, and the king. Rightly as he himself said, "Render therefore unto Caesar the things which are Caesar's, and unto God the things that are God's" (Matt. 22). Neither is there any obstacle in the Lord and king to understand the Father and the Son being designated, who are to be worshipped with one and the same honor of divinity. For he who does not honor the Son does not honor the Father who sent him (John 5). And do not join with the detractors. Meaning those who, claiming to know God the Father, refused to receive the Son of God appearing in the flesh.
[AD 407] John Chrysostom on Proverbs 24:21