Psalms 78::40 How oft did they provoke him in the wilderness, and grieve him in the desert! 41 Yea, they turned back and tempted God, and limited the Holy One of Israel.
[Patriarchs & Prophets pp 318] The people of Israel, especially the mixed multitude, would be constantly disposed to rebel against God. They would also murmur against their leader, and would grieve him by their unbelief and stubbornness, and it would be a laborious and soul-trying work to lead them through to the Promised Land. Their sins had already forfeited the favor of God, and justice called for their destruction. The Lord therefore proposed to destroy them, and make of Moses a mighty nation.
“Let Me alone, ... that I may consume them,” were the words of God. If God had purposed to destroy Israel, who could plead for them? How few but would have left the sinners to their fate! How few but would have gladly exchanged a lot of toil and burden and sacrifice, repaid with ingratitude and murmuring, for a position of ease and honor, when it was God Himself that offered the release.
But Moses discerned ground for hope where there appeared only discouragement and wrath. The words of God, “Let Me alone,” he understood not to forbid but to encourage intercession, implying that nothing but the prayers of Moses could save Israel, but that if thus entreated, God would spare His people. He “besought the Lord his God, and said, Lord, why doth Thy wrath wax hot against Thy people, which Thou hast brought forth out of the land of Egypt with great power, and with a mighty hand?”
Psalms 78:56 Yet they tempted and provoked the most high God, and kept not his testimonies. 57 But turned back, and dealt unfaithfully like their fathers: they were turned aside like a deceitful bow.