The word amen appears 13 times in the Hebrew Bible and 119 times in the New Testament as well as in the earliest Muslim writings.
The word originated in Egypt around 2500 B.C. as Amun, and meant the “Hidden One,” the name of their highest deity.
Hebrew scholars adopted the word as meaning “so it is” and passed it on to the Christians and Muslims.
At the end of a profound statement or prayer, Christians, Muslims, and Jews all say “amen”.