'Key' in the Bible

They waited [a very long time] until they became embarrassed and uneasy, but he still did not open the doors of the upper room. So [finally] they took the key and opened them, and behold, their master had fallen to the floor, dead.

“Then I will set on his shoulder the key of the house of David;When he opens no one will shut,When he shuts no one will open.

Woe to you lawyers, because you have taken away the key to knowledge (scriptural truth). You yourselves did not enter, and you held back those who were entering [by your flawed interpretation of God’s word and your man-made tradition].”

“And to the angel (divine messenger) of the church in Philadelphia write:“These are the words of the Holy One, the True One, He who has the key [to the house] of David, He who opens and no one will [be able to] shut, and He who shuts and no one opens:

Then the fifth angel sounded [his trumpet], and I saw a star (angelic being) that had fallen from heaven to the earth; and the key of the bottomless pit (abyss) was given to him (the star-angel).

And then I saw an angel descending from heaven, holding the key of the abyss (the bottomless pit) and a great chain was in his hand.