What thing soever I command you, observe to do it,.... In the manner it is commanded and directed to; the laws of God, both as to matter and manner, were to be obeyed just as they were delivered: thou shall not add thereto, nor diminish from it; neither add any customs and rites of the Heathens to them, nor neglect anything enjoined on them, see Proverbs 30:6.

The admonition to observe the whole law, without adding to it or taking from it (cf. Deuteronomy 4:2), is regarded by many commentators as the conclusion of the previous chapter. But it is more correct to understand it as an intermediate link, closing what goes before, and introductory to what follows. Strictly speaking, the warning against inclining to the idolatry of the Canaanites (Deuteronomy 12:29-31) forms a transition from the enforcement of the true mode of worshipping Jehovah to the laws relating to tempters to idolatry and worshippers of idols (ch. 13). The Israelites were to cut off not only the tempters to idolatry, but those who had been led astray to idolatry also. Three different cases are mentioned.

What thing soever I command you, observe to do it: thou shalt not add thereto, nor diminish from it.

12:5-32 The command to bring ALL the sacrifices to the door of the tabernacle, was now explained with reference to the promised land. As to moral service, then, as now, men might pray and worship every where, as they did in their synagogues. The place which God would choose, is said to be the place where he would put his name. It was to be his habitation, where, as King of Israel, he would be found by all who reverently sought him. Now, under the gospel, we have no temple or altar that sanctifies the gift but Christ only: and as to the places of worship, the prophets foretold that in every place the spiritual incense should be offered, Mal 1:11. Our Saviour declared, that those are accepted as true worshippers, who worship God in sincerity and truth, without regard either to this mountain or Jerusalem, Joh 4:21. And a devout Israelite might honour God, keep up communion with him, and obtain mercy from him, though he had no opportunity of bringing a sacrifice to his altar. Work for God should be done with holy joy and cheerfulness. Even children and servants must rejoice before God; the services of religion are to be a pleasure, and not a task or drudgery. It is the duty of people to be kind to their ministers, who teach them well, and set them good examples. As long as we live, we need their assistance, till we come to that world where ordinances will not be needed. Whether we eat or drink, or whatever we do, we are commanded to do all to the glory of God. And we must do all in the name of the Lord Jesus Christ, giving thanks to the Father through him. They must not even inquire into the modes and forms of idolatrous worship. What good would it do them to know those depths of Satan? And our inward satisfaction will be more and more, as we abound in love and good works, which spring from faith and the in-dwelling Spirit of Christ.