Notes on The Holy Gospel of Jesus Christ, According to St. Matthew (Author Bishop Richard Challoner (ed.))
5:18 Amen: That is, assuredly of a truth. . .This Hebrew word, amen, is here retained by the example and authority of all the four Evangelists. It is used by our Lord as a strong asseveration, and affirmation of the truth.
Original Douay-Rheims from Project Gutenberg - Massive cleanup of OCR problems and editing done locally.