God's Breach of Promise
When Israel refused to take God at His word concerning the land of promise He had prepared for them, when they did not mix faith with the gospel preached to them, and when they persisted in their Unbelief, God uttered terrible words to them.

He said,
"Doubtless ye shall not come into the land, concerning which I sware to make you dwell therein, save Caleb the son of Jephunneh, and Joshua the son of Nun...as for you, your carcases, they shall fall in this wilderness. And your children shall wander in the wilderness forty years, and bear your whoredoms, until your carcases be wasted in the wilderness. After the number of the days in which ye searched the land, even forty days, each day for a year, shall ye bear your iniquities, even forty years, and ye shall know my breach of promise." Numbers 14:30-34
Notice the shocking words God spoke at the end of the passage above. He said to His own people, "ye shall know my breach of promise."

WOW. Whereas He had formerly pronounced to display power such as the world had never seen when He brought Israel into the land of promise, God now set Himself against His own promise!

These words - "ye shall know my breach of promise" - have to be some of the most shocking words of the Old Testament. Not only did God withdraw Himself from His own people; He went back on His own word of promise, swaring in His wrath that they would not enter in to Canaan.
The space of time between Israel's supernatural departure from Egypt and their coming to the edge of the land of Canaan is called "the day of temptation" and "the provocation." This was the time period where, although Israel had seen the supernatural power of God on display again and again and had heard the gospel of their land of promise preached again and again, they REFUSED to believe God and enter into the land He had prepared and promised.
This story is cited by the writer of Hebrews, under the inspiration of the Holy Spirit, as part of a challenge and warning to New Testament believers to not make the same mistake that Israel made and fail, because of Unbelief, to enter into all that God had prepared for them. Notice these challenging words from Hebrews 3:7-12:
"Wherefore (as the Holy Ghost saith, To day if ye will hear his voice,
Harden not your hearts, as in the provocation, in the day of temptation in the wilderness:
When your fathers tempted me, proved me, and saw my works forty years.
Wherefore I was grieved with that generation, and said, They do alway err in their heart; and they have not known my ways.
So I sware in my wrath, They shall not enter into my rest.)
Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God."
Notice that the word of warning to believers in the passage above from Hebrews is not, "Take heed lest you sin." It is, "Take heed, lest there be in any of you an evil heart of unbelief."
It is very important that we, as New Testament believers, pay attention to ALL the things the Holy Spirit speaks to us through the Word of God! Although we Came Out of darkness, death, sin, and bondage by faith in the Gospel, there is MUCH left for us to Enter Into! Let’s not be like Israel and fail to Enter In to ALL that God has “prepared for them that love him.”