Isaiah said, “And I will place on his shoulder the key of the house of David. He shall open, and none shall shut, and he shall shut, and none shall open.” (Isa. 22:22 ESV)

The hymn O Come, O Come, Emmanuel has this line in verse 5,

O come, O Key of David, come
and open wide our heavenly home.

As the Key of David, Jesus opens to us the way to Heaven, and no one can bar that entrance. He is our access to the Father, and no one can close that way. Rejoice!

O Key of David and scepter of the House of Israel;
you open and no one can shut;
you shut and no one can open:
Come and lead the prisoners from the prison house,
those who dwell in darkness and the shadow of death.