Deuteronomy 6:16-25; Deuteronomy 7:1-6
Tempting God (v 16) means effectively putting Him on the spot to prove what He says. It is nothing less than unbelief. At Massah the people wanted to know for certain that the LORD was indeed amongst them (Exodus 17:7), whereas Jesus had no need whatsoever to throw Himself from the height of the temple to know that orders had been given to the angels concerning Him (Matthew 4:6).
According to v. 7, parents were responsible for teaching the words of the LORD to their children. Our v. 20 envisages the sons questioning their fathers. Such questions are provided for on three other occasions. In Exodus 12:26 it is the subject of the Passover (what is the way of salvation?). In Exodus 13:14 it deals with the separation which follows (why this continual separation from the world?). Finally in Joshua 4:6 it is with respect to the twelve stones taken from the Jordan and placed in Canaan (a question relating to the heavenly position of the believer and the unity of the Church as the body of Christ). Dear young friends, ask these questions! What fine replies you will receive! (vv. 21-25).
Israel was to spare nothing belonging to the Canaanites nor of their gods. This was not to satisfy the warlike and domineering spirit which generally motivates conquering nations, but because Israel was a holy people unto the LORD (v. 6).