Isaiah 65:16

So [it shall be] that he who invokes a blessing on himself in the land shall do so by saying, May the God of truth and fidelity [the Amen] bless me; and he who takes an oath in the land shall swear by the God of truth and faithfulness to His promises [the Amen], because the former troubles are forgotten and because they are hidden from My eyes. [II Cor. 1:20; Rev. 3:14.]