2 Corinthians 1:19-20

19Silas, Timothy and I told you the message about God's Son, Jesus Christ. Christ is not someone who changes his message between ‘Yes’ and ‘No’. Instead, he always says ‘Yes,’ and he does what he says.

20Christ says ‘Yes’ to all of God's promises, so that they become true. So when we pray, we say ‘Yes, amen!,’ because we know that Christ has done it. And when we do that, we are saying that God is great.