2 verse examples: Numbers 5:22 בְּמִדבַּר Is the account of the adulterous woman, who fails the test of fidelity, and her body swells up and parts “fall away” must declare: “ah-MEIN, ah-MEIN “ Second example: Deuteronomy 27:15 דּבָרים Where the Israelite tribes stand on Mt. Girizim and Mt. Ebal to declare a curse or a blessing on the people based on their obedience. After each statement (whether a blessing or a curse) the people say together: “ah-MEIN, ah-MEIN”.
We can see that tagging Amen at the end of someone's statement, prayer or declaration, is a powerful confirmation, and biblically is used with both a positive and negative connotation.
Therefore, we should take care what words we allow to come from our mouths! NT Ephesians 4:29 and James 5:22 come to mind!