Deuteronomy 1:43, commentary and pictures

After refusing to advance when bidden, Israel would not hear but rebelled directly against the commandment of the Lord and went presumptuously up into the hill to battle. That presumptuous attack was made without God's appointed leadership and presence — without Moses, without the cloudy pillar that was the symbol of the divine presence, and without the ark — and ended in rout with thousands slain. This record in the first chapter explains why the Lord refused to bring the adult army that left Egypt into the promised land. The failure of that generation means that the Lord's promises are upon condition of obedience, and disobedience forfeits the promise.

By contrast, the later advance was made in obedience with Moses strengthening hearts with words of hope and faith, with the Son of God enshrined in the cloudy pillar leading the way and the sacred ark accompanying the host. This shows that when His people obey His requirements and go forward humbly trusting in Him, God works for them in as signal a manner even when obstacles seem insurmountable.

The verse is written for the admonition of those upon whom the ends of the world are come and is to be read in full, with Deuteronomy 7 and Deuteronomy 8. It belongs with the warning about the Lord rising up to do His work, His strange work, the warning not to be mockers, and the consumption determined upon the whole earth. As admonition it warns against rejecting the Lord's guidance and following human judgment — following His guidance only up to the point that agrees with one's own judgment while holding fast to one's own ideas and refusing to be molded after the Lord's similitude. Instead God's people must look to Christ's example in self-denial and self-sacrifice, live not to please themselves, and meet the Lord's standard of perfection of character.