The Binding of Isaac is found in Genesis, specifically Genesis 22.
In the narrative, God tests Abraham by commanding him to offer Isaac as a sacrifice on Mount Moriah. Abraham binds Isaac to an altar, but an angel stops him before the sacrifice; a ram is then offered instead. This is why the episode is commonly called the Akedah, Hebrew for “binding.”
In Jewish worship, Genesis 22 is traditionally read on the second day of Rosh Hashanah, not the first. The first-day Torah reading is Genesis 21, concerning the birth and early life of Isaac. The Binding of Isaac’s themes of obedience, testing, mercy, and remembrance help explain its place in the High Holy Day liturgy.
A common mix-up is confusing the Torah book with the weekly portion: the episode appears in Parashat Vayeira, but Vayeira is a portion of Genesis, not a separate book.