Numbers 32:15, commentary and pictures

Moses spoke these words to Gad and Reuben when they wished to sit still while their brethren went to war, abandoning their duty to fight alongside Israel and discouraging Israel from entering the land the Lord had given them. Their course repeated the sin of their fathers when sent from Kadesh-barnea to see the land and when they went up to the Valley of Eschol and discouraged Israel from entering. Because the fathers did not wholly follow the Lord, His anger was kindled and He made Israel wander forty years in the wilderness until the evil generation was consumed, sparing only Caleb and Joshua who wholly followed Him.

Moses warned the new generation risen up in their fathers' stead as an increase of sinful men to augment fierce anger. If they turned away from following Him, He would yet again leave Israel in the wilderness, and they would destroy all the people. Turning away means failing to keep commitment and seeking personal ease while others bear hardship, which belongs with unbelief and brings grave consequences and the Lord's displeasure.

The Lord revealed here is a jealous God. He bears long with the sins and transgressions of His people, yet His promises and the advance of His work rest upon condition of obedience, believing Him, being doers of His word, and keeping His commandments. The same principle applies now: because this generation is disobedient, unthankful and unholy as ancient Israel was, His work is hindered, time is prolonged and the sealing time is delayed so that all may hear the last message of mercy proclaimed with a loud voice and those who have not heard the truth may have a chance to hear and be converted, after which the great work will go forward. Had His people walked in His counsel, the work would have advanced and the messages of truth would have been borne to all people dwelling on the face of the whole earth.