"Therefore, since we also have such a large cloud of witnesses surrounding us, let us lay aside every hindrance and the sin that so easily ensnares us. Let us run with endurance the race that lies before us, keeping our eyes on Jesus, the pioneer and perfecter of our faith. For the joy that lay before him, he endured the cross, despising the shame, and sat down at the right hand of the throne of God."
Hebrews 12:1-2 CSB
“‘For the joy.’ What joy? What was waiting for Jesus on the other side of the cross? The joy of seeing his people forgiven. Remember the whole point of Hebrews—Jesus is the high priest to end all high priests, who has made the final atoning sacrifice to completely cover the sins of his people so that they are provided for ‘to the uttermost’ (7:25). And remember what the writer means when he speaks of Jesus sitting down at God's right hand, at the end of Hebrews 12:2. Elsewhere the writer to the Hebrews is explicit about what this signifies:
After making purification for sins, he sat down at the right hand of the Majesty on high. (1:3)Now the point is what we are saying is this: we have such a high priest, one who is seated at the right hand of the throne of the Majesty in heaven. (8:1)But when Christ had offered for all time a single sacrifice for sins, he sat down at the right hand of God. (10:12)
“In all these texts, Jesus's seating at God's right hand is associated with his priestly atoning work. The priest was the bridge between God and humanity. He reconnected heaven and earth. Jesus did this supremely through his climactic and final sacrifice of himself, purifying his people once and for all, cleansing them of their sins. It was the joyous anticipation of seeing his people made invincibly clean that sent him through his arrest, death, burial, and resurrection. When we today partake of that atoning work, coming to Christ for forgiveness, communing with him despite our sinfulness, we are laying hold of Christ's own deepest longing and joy (Kindle location 473, Dane Ortlund, Gentle and Lowly).”
Christ's “own joy, comfort, happiness, and glory are increased and enlarged by his showing grace and mercy, in pardoning, relieving, and comforting his members here on earth”
(Thomas Goodwin, The Heart of Christ).