It's understood that Paul wrote the book of Hebrews and I believe he did because of his close connection with Christ after his conversion on the road to Damascus. He had a real encounter with Christ on that road and kept his connection until his death.
Hebrews 2:17,18 "Therefore in all He had to be made like His brethren, that He might be a merciful and faithful High Priest in things pertaining to God, to make propitiation for the sins of the people. For in that He himself has suffered, being tempted, He is able to aid those who are tempted." Jesus was made like us, so that He could be a merciful and faith High Priest to His Father so that He could forgive us for out sins. Because He suffered and was tempted, He is able to help us who also are tempted. That is wonderful to know that we do have a faithful and merciful High Priest in heaven interceding for us.
Hebrews 3:14,15 "For we have become partakers of Christ if we hold the beginning of our confidence steadfast to the end, while it is said: Today, if you will hear His voice, do not harden your hearts as in the rebellion." If we hold the beginning of our confidence steadfast to the end we have become a partaker of Christ, 2 Peter 2:4 also says that if we believe His promises we will be a partaker of His nature. Harden not your hearts as in the rebellion, is speaking of how the Israelites hardened their hearts and rebelled against God when He wanted them to enter Canaan and they said there were giants in the land and refused to obey God's direction.
Hebrews 4:9-16 "There remains therefore a rest for the people of God, for he who has entered His rest has himself also ceased from his work as God did from His. Let us therefore be diligent to enter that rest, lest anyone fall according to the same example of disobedience. For the word of God is living and powerful, and sharper than any two-edged sword, piercing even to the division of soul and spirit, and of joints and marrow, and is a discerner of the thoughts and intents of the heart. And there is no creature hidden from His sight, but all things are naked and open to the eyes of Him to whom we must give account. Seeing then that we have a great High Priest who has passed through the heavens, Jesus the Son of God, let us hold fast our confession. For we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin. Let us therefore come boldly to the throne o grace, may obtain mercy and find grace to help in time of need." Here is some verses in Hebrews that you may have never noticed before. 'There remains therefore a rest for the people of God.' What is that rest? 'For he who has entered His rest has himself also ceased from his work as God did from His'. When did God rest from His work? Check out Exodus 20:8 and see if you can come up with the answer. All things are open to the eyes of God to whom we must give account.
I know this was probably a hard set of promises to understand and some might not believe them but the Word of God is sure and steadfast and we can believe every word. This is where our power to overcome sin comes in. Without believing, we have no power. Please be assured that what God says He will do or has already done. It is so important!!! Grandma Joan.