The verb sagar has two main uses. In its primary sense it means to shut, close, or lock — closing a door, gate, or other opening. In its extended sense it means to deliver someone over or hand them into another's power — as though one shuts the person into the hand of another. Both senses involve the idea of enclosure and confinement.
The shutting actions of God reveal his sovereign control over situations that seem closed. God shut Noah's ark (Genesis 7:16) — a divine act of protection. He shut the mouths of lions for Daniel (Daniel 6:22). Conversely, God can shut up the heavens in judgment (Deuteronomy 11:17). The New Testament promise that Christ holds 'the key of David' and what he opens no one can shut, and what he shuts no one can open (Revelation 3:7) builds on this imagery. Every door God closes is an act of sovereign grace or judgment; every door he opens is an invitation to life.