There are those two forlorn little words again: “if only.” The psalmist is remembering what happened to God’s people when they didn’t listen and hardened their hearts. God had delivered them from slavery in Egypt with the miraculous parting of the Red Sea. He led them through the desert, feeding them manna and quail and producing water from a rock. They had witnessed God’s provision firsthand. But when they reached the border of Canaan, the Promised Land, they grew afraid. In His anger at their unbelief, God swore that–– except for Joshua and Caleb who followed Him wholeheartedly and believed in His greatness (see Numbers 14:20-30)––none of that generation would enter His rest. What a stark, hopeless forecast.
We also have been urged, “See to it, brothers, that none of you has a sinful, unbelieving heart that turns away from the living God” (Hebrews 3:12). Were it not for the fact that all God’s promises have been fulfilled in Jesus, we too would despair. But promised rest awaits us, if only we will hear His voice.