"'Do not harden your hearts, as when they provoked Me'" (Heb 3:15). "Who provoked Him when they heard?" (:16). "Was it not those who sinned, whose bodies fell in the wilderness" (:17) and "who were disobedient?" (:18). "They were not able to enter because of unbelief" (:19). Therefore, be careful "that there not be in any one of you an evil, unbelieving heart that falls away from the living God" (:12). Make sure that "none of you will be hardened by the deceitfulness of sin" (:13). Disobedience results in sin due to hardness and unbelief. It leads to falling away from God. But why would the author of Hebrews bring this up to Jews who were now living under a New Covenant where the old one had been superseded? They would know not to make those same mistakes again. However, the reason is that "these things happened as examples for us, so that we would not crave evil things as they craved" (1Co 10:6). They were not to "be idolaters" (:7). They said to Aaron, "'Come, make us a god who will go before us; as for this Moses . . . we do not know what has become of him'" (Ex 32:1). "They were drinking from a spiritual rock which followed them; and the rock was Christ" (1Co 10:4). The lesson is "that the Lord, after saving a people out of the land of Egypt, subsequently destroyed those who did not believe" (Jude 5).
One event in the wilderness was when they didn't have any water. God told Moses, "'Take the rod . . . and speak to the rock before their eyes, that it may yield its water'" (Nu 20:8). "Then Moses lifted up his hand and struck the rock twice with his hand" (:11). But he was told to only speak to it. God then responded, "'Because you have not believed Me, to treat Me as holy in the sight of the sons of Israel, therefore you shall not bring this assembly into the land which I have given them'" (:12). Later Moses recounted, "'The Lord was angry with me also on your account, saying 'Not even you shall enter there''" (Dt 1:37). The decision was that they "'shall by no means see the land which I swore to their fathers . . . but My servant Caleb, because he had a different spirit and followed Me fully'" (Nu 14:23-24). Entering the promised land is a picture of God's plan. "His works were finished from the foundation of the world" (Heb 4:3). "By the seventh day God completed His work which He had done, and He rested on the seventh day from all His work which He had done" (Ge 2:2). The land God was giving Israel is symbolic of the result of the work he had finished which he was now resting from. However, "to whom did He swear that they would not enter His rest, but to those who were disobedient? So we see that they were not able to enter because of unbelief" (Heb 3:18-19). "Therefore, let us fear if, while a promise remains of entering His rest, any one of you may seem to come short of it" (4:1). "We who have believed enter that rest" (:3).