“While it is said, To day if ye will hear his voice, harden not your hearts, as in the provocation. For some, when they had heard, did provoke: howbeit not all that came out of Egypt by Moses.” Hebrews 3:15-16 KJV
The writer is saying “exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin.” Hebrews 3:13
The deceitfulness of sin
They steeled themselves against God’s love through unbelief and complained against him, and deceived and misled others.
What really happened in the provocation?
“For some, when they had heard, did provoke: howbeit not all that came out of Egypt by Moses.” Hebrews 3:16
How did they provoke Him?
Through unbelief; they tried his patience, disobeyed him and chose not to believe or trust him. Some, when they heard the word, provoked him, tempted him and proved him, and God said, “Wherefore I was grieved with that generation, and said, They do alway err in their heart; and they have not known my ways.” Hebrews 3:10
“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.” Hebrews 3:7-8
Christ will save us only if we trust him, besides that he’ll profit us nothing. Hebrews 3:6 says, “But Christ as a son over his own house; whose house are we, if we hold fast the confidence and the rejoicing of the hope firm unto the end.”
- hold fast the confidence, (trust) and the rejoicing, (joy) of the hope, (the Lord) firm unto the end.
Our joy and our trust is in the Lord.
“Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.” Hebrews 3:12
Never forget the warning, “To day if ye will hear his voice, harden not your hearts, as in the provocation.”
Jesus Christ is greater than Moses, and his house better
“Wherefore, holy brethren, partakers of the heavenly calling, consider the Apostle and High Priest of our profession, Christ Jesus;  Who was faithful to him that appointed him, as also Moses was faithful in all his house.  For this man was counted worthy of more glory than Moses, inasmuch as he who hath builded the house hath more honour than the house.” Hebrews 3:1-3