I cannot believe no one has mentioned Aaron’s answer to Moses after the Golden Calf incident?!
Oh, and just to add to my former comment:
A Jewish folktale actually attempts to cut Aaron some slack by making his (lame and feeble) excuse literally true.

From Louis Ginzberg’s
The Legends of the Jews:
Strange as it may seem that Israel should set out to worship this idol at the very time when God was busied with the preparation of the two tables of the law, still the following circumstances are to be considered. When Moses departed from the people to hasten to God to receive the Torah, he said to them: “
Forty days from to-day I will bring you the Torah.” But at noon on the fortieth day Satan came, and with a wizard’s trick conjured up for the people a vision of Moses lying stretched out dead on a bier that floated midway between earth and heaven. Pointing to it with their fingers, they cried: “
This is the man Moses that bought us up out of the land of Egypt.” Under the leadership of the magicians Jannes and Jambres, they appeared before Aaron, saying: “
The Egyptians were wont to carry their gods about with them, to dance and play before them, that each might be able to behold his gods; and now we desire that thou shouldst make us a god such as the Egyptians had.” When Hur, the son of Miriam, whom Moses during his absence had appointed joint leader of the people with Aaron, owing to his birth which placed him among the notables of highest rank, beheld this, he said to them: “
O ye frivolous ones, you are no longer mindful of the many miracles God wrought for you.” In their wrath, the people slew this pious and noble man; and, pointing out his dead body to Aaron, they said to him threateningly: “
If thou wilt make us a god, it is well, if not we will dispose of thee as of him.” Aaron had no fear for his life, but he thought: “
If Israel were to commit so terrible a sin as to slay their priest and prophet, God would never forgive them.” He was willing rather to take a sin upon himself than to cast the burden of so wicked a deed upon the people. He therefore granted them their wish to make them a god, but he did it in such a way that he still cherished the hope that this thing might not come to pass. Hence he demanded from them not their own ornaments for the fashioning of the idol, but the ornaments of their wives, their sons, and their daughters, thinking: “
If I were to tell them to bring me gold and silver, they would immediately do so, hence I will demand the earrings of their wives, their sons, and their daughters, that through their refusal to give up their ornaments, the matter might come to nought.” But Aaron’s assumption was only in part true; the women indeed did firmly refuse to give up their jewels for the making of a monster that is of no assistance to his worshippers. As a reward for this, God gave the new moons as holidays to women, and in the future world too they will be rewarded for their firm faith in God, in that, like the new moons, they too, may monthly be rejuvenated. But when the men saw that no gold or silver for the idol was forthcoming from the women, they drew off their own earrings that they wore in Arab fashion, and brought these to Aaron.
No living calf would have shaped itself out of the gold of these earrings, if a disaster had not occurred through an oversight of Aaron. For when Moses at the exodus of Israel from Egypt set himself to lifting the coffin of Joseph out of the depths of the Nile, he employed the following means: He took four leaves of silver, and engraved on each the image of one of the beings represented at the Celestial Throne,-the lion, the man, the eagle, and the bull. He then cast on the river the leaf with the image of the lion, and the waters of the river became tumultuous, and roared like a lion. He then threw down the leaf with the image of man, and the scattered bones of Joseph united themselves into an entire body; and when he cast in the third leaf with the image of the eagle, the coffin floated up to the top. As he had no use for the fourth leaf of silver with the image of the bull, he asked a woman to store it away for him, while he was occupied with the transportation of the coffin, and later forgot to reclaim the leaf of silver. **This was now among the ornaments that the people brought to Aaron, and it was exclusively owing to this bull’s image of magical virtues, that a golden bull arose out of the fire into which Aaron put the gold and silver.
When the mixed multitude that had joined Israel in their exodus from Egypt saw this idol conducting itself like a living being, they said to Israel: “
This is thy God, O Israel.”** The people then betook themselves to the seventy members of the Sanhedrin and demanded that they worship the bull that had led Israel out of Egypt. “
God,” said they, “
had not delivered us out of Egypt, but only Himself, who had in Egypt been in captivity.” The members of the Sanhedrin remained loyal to their God, and were hence cut down by the rabble. The twelve heads of the tribes did not answer the summons of the people any more than the members of the Sanhedrin, and were therefore rewarded by being found worthy of beholding the Divine vision.
Note how exonerated Aaron is of all heavy guilt: the golden calf only came into being because Aaron overlooked the miraculous silver leaf.
