Isaac was twenty-five years old when his father took him up the mountain to die. He didn't resist.
According to Josephus, this is what makes the Akedah (עקידה), the Binding of Isaac, so extraordinary—not just that Abraham was willing to sacrifice his son, but that Isaac agreed to it. Josephus gives Isaac a speech that appears nowhere in the Torah, and it is stunning in its composure: "He was not worthy to be born at first, if he should reject the determination of God and of his father."
The setup was devastating. Abraham had waited a hundred years for this child (Genesis 21:5). Isaac was everything—the promised heir, the boy who embodied every blessing God had ever given. And then God asked for him back. Not metaphorically. As a burnt offering on Mount Moriah.
Abraham told no one. Not Sarah. Not his servants. He knew that if anyone found out, they would stop him. So he packed the wood, took two servants and Isaac, and walked for three days. On the third day, he saw the mountain—the same mountain, Josephus notes, where King David would later build the Temple—and left the servants behind.
Isaac noticed there was no animal for the sacrifice. Abraham answered with the only honest thing he could say: "God will provide Himself an offering" (Genesis 22:8). Then he told his son the truth. Josephus gives Abraham a long, anguished speech—a father explaining to his child why he must die. He had prayed endlessly for a son. He had raised Isaac to manhood. And now God required him as a testimony of Abraham's devotion.
Isaac walked to the altar willingly. The knife was raised. And God called out, loud enough to stop a father's hand, and said it had never been about the boy's blood—only about the willingness to obey. A ram appeared. Abraham and Isaac sacrificed it together, embraced each other, and went home to Sarah. They lived, Josephus says, happily—with God assisting them in all things they desired.