Verse 20. - Iron furnace - furnace for smelting iron: "figure of burning torment in Egypt" (Herxheimer). This reference to the smelting of iron shows that, though the implements of the ancient Egyptians were mostly of copper, iron must also have been in extensive use among them. Other references to the use of iron are to be found in the Pentateuch; see Genesis 4:22; Leviticus 26:19; Numbers 35:16; Deuteronomy 3:11; Deuteronomy 8:9; Deuteronomy 19:5; Deuteronomy 27:5 (Goguet, 'Origine des Lois,' 1:172; Wilkinson, 'Ancient Egypt,' 1:169; 2:155). To be unto him a people, etc. (cf. Exodus 19:4-6; Deuteronomy 7:6).

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.But the Lord hath taken you, and brought you forth out of the iron furnace,.... The allusion is to the trying and melting of metals, and fleeing them from dross, by putting them into furnaces strongly heated, some of which are of earth, others of iron; the word, as the Jewish writers (g) observe, signifies such an one in which gold and silver and other things are melted; see Psalm 12:6 even "out of Egypt"; which is here compared to an iron furnace, because of the cruelty with which the Israelites were used in it, the hardships they were put under, and the misery and bondage they were kept in; but out of all the Lord brought them, as he does all his people sooner or later out of their afflictions, sometimes called the furnace of affliction, Isaiah 48:10 where their graces are tried, and they are purged, purified, and refined from their dross and tin. This the Lord did to Israel, he brought them out of their distressed state and condition:

to be unto him a people of inheritance, as ye are this day: to be the Lord's inheritance, as they now were, Deuteronomy 32:9 as well as they were quickly to inherit the land of Canaan, for which they were brought out of the land of Egypt; and indeed they were already, even that day, entered on their inheritance, the kingdom of the Amorites being delivered into their hands.

(g) Maimon. & Bartenora in Misn. Celim. c. 8. sect. 9. & Jarchi in loc.