This is the verse that unlocks the whole story. Targum Pseudo-Jonathan fills in what the plain Hebrew leaves as silence: "For Aaron had seen Hur slain before him, and was afraid; and he builded an altar before him, and Aaron cried with doleful voice" (Exodus 32:5).
Who was Hur, and what happened?
Hur was Miriam's son — Moses's nephew, a leader of the people, one of the two men Moses had left in charge of the camp along with Aaron (Exodus 17:10-12, 24:14). When the mob came demanding a god, Hur resisted. He rebuked them. He refused to participate. And the mob killed him. His body, the midrashim record (Vayikra Rabbah 10:3, c. 600 CE), lay before Aaron as a warning.
Aaron was next. The mob turned to him with the same demand, and Aaron saw the blood of his nephew still wet on the ground. He was afraid — not for himself, the sages said, but for the people. Aaron reasoned: if I refuse like Hur, they will kill me too, and then they will bear the sin of killing a priest, and no atonement for that crime is possible. Better to stall. Better to build an altar and announce a feast for the next morning, hoping Moses will descend in the night.
The targum adds: Aaron cried with a doleful voice. He announced the feast not in triumph but in grief. He named it a "feast before the Lord" — not the calf, but the Lord — hoping the people would hear the correction. They did not. They heard what they wanted.
The midrashic tradition is unsparing about the choice Aaron made. It was not righteous. It delayed but did not prevent. And it left Aaron bearing a guilt Moses would have to atone for on the mountain with forty more days of prayer.
The Maggid takes this home: fear is not always cowardice. Sometimes fear is a priest trying to save his people and getting it half-right. The story does not exonerate Aaron, but it refuses to flatten him into a villain.