(20) Thou shalt fear the Lord thy God; him shalt thou serve.--In the New Testament, "Thou shalt worship the Lord thy God, and him only shalt thou serve." It was our Lord's last answer to the tempter in the wilderness. The order of the Hebrew gives the emphasis. "Jehovah thy God shalt thou fear, Him shalt thou serve, and to Him shalt thou cleave;" "and (adds Rashi) after all these qualities are established in thee, then thou shalt swear by His name." At least His name would not be profaned in such a case.

Verse 20. - Reverting to his main theme, Moses anew exhorts Israel to fear Jehovah their God, and to show true reverence to him by serving him, by cleaving to him, and by swearing in his Name (cf. Deuteronomy 4:4; Deuteronomy 6:13; Acts 11:23). Such reverence was due from Israel to God, because of the great things he had done for them, and those terrible acts by which his mighty power had been displayed on their behalf.

10:12-22 We are here taught our duty to God in our principles and our practices. We must fear the Lord our God. We must love him, and delight in communion with him. We must walk in the ways in which he has appointed us to walk. We must serve him with all our heart and soul. What we do in his service we must do cheerfully, and with good will. We must keep his commandments. There is true honour and pleasure in obedience. We must give honour to God; and to him we must cleave, as one we love and delight in, trust in, and from whom we have great expectations. We are here taught our duty to our neighbour. God's common gifts to mankind oblige us to honour all men. And those who have themselves been in distress, and have found mercy with God, should be ready to show kindness to those who are in the like distress. We are here taught our duty to ourselves. Circumcise your hearts. Cast away all corrupt affections and inclinations, which hinder you from fearing and loving God. By nature we do not love God. This is original sin, the source whence our wickedness proceeds; and the carnal mind is enmity against God, for it is not subject to the law of God, neither indeed can be; so then they that are in the flesh cannot please God, Ro 8:5-9. Let us, without delay or reserve, come and cleave to our reconciled God in Jesus Christ, that we may love, serve, and obey him acceptably, and be daily changed into his image, from glory to glory, by the Spirit of the Lord. Consider the greatness and glory of God; and his goodness and grace; these persuade us to our duty. Blessed Spirit! Oh for thy purifying, persevering, and renewing influences, that being called out of the state of strangers, such as our fathers were, we may be found among the number of the children of God, and that our lot may be among the saints.Thou shalt fear the Lord thy God,.... Which includes the whole worship of him, external and internal:

him shalt thou serve; heartily and sincerely, according to his revealed will, and him only:

and to him shall thou cleave; and not turn aside to follow other gods, and worship them:

and swear by his name; and his only, whenever it is necessary to take an oath, which should not be done rashly or on trivial accounts; and never by any creature, but by the living God; see Deuteronomy 6:13.