Exodus 32:5

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.

Aaron ... built an altar before it - `like that which still exists before the nostrils of the sphinx' (Stanley, 'Jewish Church,' p. 150).

Aaron made proclamation ... Tomorrow is a feast to the Lord - not to Apis or to Osiris, as enshrined in his image, but to Yahweh. This is a remarkable circumstance, strongly confirmatory of the view, that they had not renounced the worship of Yahweh, 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. Such at least seems to have been the view of Aaron, whose language on any other hypothesis is inexplicable. But whatever he meant, the people regarded it as an idol; and hence, they are severely condemned as guilty of a gross sin in every part of Scripture where allusion is made to the golden calf.