Psalm 126  " When the LORD brought back the captive ones of Zion"  At first they were confused, it felt like a dream.  They couldn't believe that it was actually happening.  But when they awoke it did not evaporate like a vision in the night. Their return to Jerusalem was real!  And they rejoiced!  Laughter and joy filled the air.  Praise to The Lord came grudgingly from their neighbors, but gladly from their own tongues.  This same joy is given to those of us who are bought out of the captivity to sin and death, into the Kingdom of Christ.  We praise Him!  "The Lord has done great things for us; We are glad." ( v3)
Remember this people of God. Sing this song every time you come into His house. Remember and rejoice anew that you have been delivered from captivity.  The Lord has rescued you and returned you to Himself.  The Lord has done great things for me.  I am glad!

Hebrews 3 The writer speaks to the "holy brethren" , the ones Jesus is not ashamed to call His brothers, for they have the same Father, He came to share flesh and blood with them, to die for them, to render the devil powerless against them, to make atonement for them.  Those who are "partakers of a heavenly calling".  They share, participate in, take of,  the invitation to brotherhood.  They take the Name that He gives them: brother, sister, family.
"consider Jesus, the Apostle and High Priest of our confession".  Consider - observe fully, behold, discover, perceive - Jesus!  He is the Apostle - the sent One, the ambassador; He is the High Priest - the chief of priests, the holiest of those called to be holy.
What are we to observe?
"He was faithful to Him Who appointed Him." (v2)
"He has been counted worthy of more glory than Moses" ( v3)
"but Christ was faithful as a Son over His house whose house we are" (v6)

We are "partakers of Christ, if we hold fast the beginning of our assurance firm until the end" ( v14)
The nation of Israel hardened their hearts against God.  They tested Him. They went astray.  They provoked Him, irritated Him, exasperated Him - with sin, with disobedience, and with unbelief.
Therefore they could not enter His rest.
We are called to hold fast to Christ, "lest there should be in any one of you an evil, unbelieving heart, in falling away from the living God."  Our hearts can be hardened too, "by the deceitfulness of sin."
So we must listen to His voice and not harden our hearts.  Hold fast - remember and hang on to - the beginning of our assurance - the support and confidence we have in Him - until the end. A steadfast, stable, sure faith in Christ alone.  He is faithful to the Father, faithful to us, His house, and worthy of all glory and praise.  Observe Him. Discover Him. Partake of Him.  Hold firm in Him.  Amen.