An allusion is a literary device in which the author makes a reference to a person, place, or event that has historical, literary or cultural significance. The reference is usually not explained. It is assumed the audience will understand the reference. For instance, many popular TV shows such as "The Simpsons" and "Family Guy" often make allusions to Shakespeare.
Elie Wiesel makes many allusions to the Torah in chapter 5 of the book Night. He also makes many references to Jewish customs and holidays.
One allusion that is made frequently in this chapter is to the Kaddish. It is sometimes referred to as the Mourner's Kaddish. It is a prayer that is often used when someone has died. Here is the text of that prayer:
"May His great Name grow exalted and sanctified (Cong: Amen.) in the world that He created as He willed. May He give reign to His kingship in your lifetimes and in your days and in the lifetimes of the entire Family of Israel, swiftly and soon. Now say: (Amen. May His great Name be blessed forever and ever.) Blessed, praised, glorified, exalted, extolled, Blessed is He. beyond any blessing and song, praise and consolation that are uttered in the world. Now say: Amen. May there be abundant peace from Heaven and life upon us and upon all Israel. Now say: Amen. He Who makes peace in His heights, may He make peace, upon us and upon all Israel. Now say: Amen."
Elie Wiesel also references Rosh Hashanah, which is in September. It is the Jewish new year. It signals the beginning of ten days of atonement, which is also known as Yom Kippur. Yom Kippur is also alluded to in chapter 5.
Elie makes reference to several stories found in Genesis in the Bible. They would also be found in the Torah and the Tanakh. The story of Sodom and Gomorrah is the story of two cities being destroyed by God's wrath because He could not find ten righteous men in those cities. This account occurs throughout the Hebrew Bible (Tanakh). Wiesel also references the account of Noah which is found in Genesis. God had become displeased with man, whose thoughts were only of wickedness, and sent a flood to destroy the earth. Only Noah, his family, and two of every kind of animal were spared. Wiesel alludes to Adam and Eve, found in the book of Genesis. They were the first recorded man and woman, and they disobeyed God. This caused them to have to leave Eden. All of the Biblical accounts he references are of God's wrath or judgment because he believes God has turned His back on His people in the concentration camps.