Verse 21. - When. Hebrews אֲֶשר. The relative pronoun here is sometimes equivalent to "when," as in Deuteronomy 11:6; 1 Kings 8:9. Gesenius would translate "if that," and Keil would render by quod.

4:20-24 It is the duty of parents to tell their children betimes of the words and works of God, that they may be trained up in the way they should go. In all the instruction parents give their children, they should teach them to fear God. Serious godliness is the best learning. Are we not called, as much as the Israelites, to praise the loving-kindness of our God? Shall we not raise a pillar to our God, who has brought us through dangers and distresses in so wonderful a way? For hitherto the Lord hath helped us, as much as he did his saints of old. How great the stupidity and ingratitude of men, who perceive not His hand, and will not acknowledge his goodness, in their frequent deliverances!And he spoke unto the children of Israel, saying,.... At the same time he set up the stones:

when you children shall ask their fathers in time to come, saying,

What mean these stones? See Gill on Joshua 4:6.