And when Aaron saw it, he built an altar before it; and Aaron made proclamation, and said, To morrow is a feast to the LORD.

Wesley's Notes

32:5 And Aaron built an altar before it, and proclaimed a feast - A feast of dedication; yet he calls it a feast to Jehovah; for, as brutish as they were, they did not design to terminate their adoration in the image; but they made it for a representation of the true God, whom they intended to worship in and through this image. And yet this did not excuse them from gross idolatry, no more than it will excuse the Papists, whose plea it is, that they do not worship the image, but God by the image; so making themselves just such idolaters as the worshippers of the golden calf, whose feast was a feast to Jehovah, and proclaimed to be so, that the most ignorant and unthinking might not mistake it.

Jamieson-Fausset-Brown Bible Commentary

5, 6. Aaron made proclamation, and said, To-morrow is a feast to the Lord-a remarkable circumstance, strongly confirmatory of the view that they had not renounced the worship of Jehovah, but in accordance with Egyptian notions, had formed an image with which they had been familiar, to be the visible symbol of the divine presence. But there seems to have been much of the revelry that marked the feasts of the heathen.

Matthew Henry's Concise Commentary

32:1-6 While Moses was in the mount, receiving the law from God, the people made a tumultuous address to Aaron. This giddy multitude were weary of waiting for the return of Moses. Weariness in waiting betrays to many temptations. The Lord must be waited for till he comes, and waited for though he tarry. Let their readiness to part with their ear-rings to make an idol, shame our niggardliness in the service of the true God. They did not draw back on account of the cost of their idolatry; and shall we grudge the expenses of religion? Aaron produced the shape of an ox or calf, giving it some finish with a graving tool. They offered sacrifice to this idol. Having set up an image before them, and so changed the truth of God into a lie, their sacrifices were abomination. Had they not, only a few days before, in this very place, heard the voice of the Lord God speaking to them out of the midst of the fire, Thou shalt not make to thyself any graven image? Had they not themselves solemnly entered into covenant with God, that they would do all he had said to them, and would be obedient? ch. 24:7. Yet before they stirred from the place where this covenant had been solemnly made, they brake an express command, in defiance of an express threatening. It plainly shows, that the law was no more able to make holy, than it was to justify; by it is the knowledge of sin, but not the cure of sin. Aaron was set apart by the Divine appointment to the office of the priesthood; but he, who had once shamed himself so far as to build an altar to a golden calf, must own himself unworthy of the honour of attending at the altar of God, and indebted to free grace alone for it. Thus pride and boasting were silenced.