Deut 4:9-24. The purpose of the experience at Horeb (v. 9-14). It is easy to forget what God has done for us or to teach our children, but this is our spiritual duty. Prohibition against idolatry (v. 15-24; Rom 1:18-23). It is God who we must worship and serve. Theory on why Moses and Aaron didn't enter promised land (Deut 4:21; Num 20:7-12).
