Exodus 32:5

Overview - Exodus 32
1	The people, in the absence of Moses, cause Aaron to make a calf.
7	God informs Moses, who intercedes for Israel, and prevails.
15	Moses comes down with the tables.
19	He breaks them.
20	He destroys the calf.
22	Aaron's excuse for himself.
25	Moses causes the idolaters to be slain.
30	He prays for the people.

Exodus 32:5  (King James Version)
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.