(15) Ye saw no manner of similitude.--The worship of the invisible Jehovah is here specially insisted on. The difficulty of learning to worship one whom we cannot see is, happily, one which our education does not enable us to realise in its relation to Israel of old. All nations had their visible symbols of deity. Centuries afterwards the world described the followers of Christ as Atheists, because they had no visible God. It is especially recorded in praise of Moses that "he endured as seeing Him who is invisible" (Hebrews 11:27).

Verses 15-20. - As the people had seen no form or figure when God spake to them, so they were to beware for their very lives (cf. ver. 9) of acting corruptly by making any kind of image, whether of man or of beast, for the purpose of worshipping God as represented by it; they were also to beware of being so attracted by the splendor of the heavenly bodies as to be forcibly seduced to worship them and offer them religious service. They were not in this respect to imitate the heathen; for God, who had delivered them out of the furnace of Egyptian bondage, had taken them for himself to be his special possession; and therefore they were to take heed not to forget the covenant of Jehovah their God, nor to offend him by making any image or representation of him as the object of worship. Among the heathen, and especially in Egypt, images were the very pillar and support of religion; but in Israel, as God had revealed himself to them without form, it was as a spirit he was to be worshipped, and not under any outward representation.

4:1-23 The power and love of God to Israel are here made the ground and reason of a number of cautions and serious warnings; and although there is much reference to their national covenant, yet all may be applied to those who live under the gospel. What are laws made for but to be observed and obeyed? Our obedience as individuals cannot merit salvation; but it is the only evidence that we are partakers of the gift of God, which is eternal life through Jesus Christ, Considering how many temptations we are compassed with, and what corrupt desires we have in our bosoms, we have great need to keep our hearts with all diligence. Those cannot walk aright, who walk carelessly. Moses charges particularly to take heed of the sin of idolatry. He shows how weak the temptation would be to those who thought aright; for these pretended gods, the sun, moon, and stars, were only blessings which the Lord their God had imparted to all nations. It is absurd to worship them; shall we serve those that were made to serve us? Take heed lest ye forget the covenant of the Lord your God. We must take heed lest at any time we forget our religion. Care, caution, and watchfulness, are helps against a bad memory.Take ye therefore good heed unto yourselves,.... As to keep all the laws given them, so particularly to avoid idolatry:

for ye saw no manner of similitude on the day the Lord spake unto you in Horeb out of the midst of the fire; and therefore, as they had nothing that directed and led them, so they had nothing that could be a temptation to them, to make any form or likeness, and worship it.