Exodus 32:5 would be the verse supporting YHWH as the object of worship.
Exodus 32:5 When Aaron saw this, he built an altar before it. And Aaron made a proclamation and said, “Tomorrow shall be a feast to the Lord.”
Benson Commentary
Exodus 32:5. "Aaron built an altar — Being borne down with the stream; and proclaimed a feast — Namely, of dedication; yet he calls it a feast to Jehovah — By which it is still more evident that the people did not intend to terminate their adoration in the image, but designed to worship the true God in and by this calf, which they meant to consider as only a visible token of God’s presence with them, and a medium by which to convey their worship to him."
Barnes Notes on the Bible
"It is expressly said that they yielded to the idolatry of Egypt while they were in bondage Joshua 24:14; Ezekiel 20:8; Ezekiel 23:3, Ezekiel 23:8; and this is in keeping with the earliest Jewish tradition (Philo). In the next verse, Aaron appears to speak of the calf as if it was a representative of Yahweh - "Tomorrow is a feast to the Lord." The Israelites did not, it should be noted, worship a living Mnevis, or Apis, having a proper name, but only the golden type of the animal."
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 Poole's Commentary
"When Aaron saw, i.e. observed with what applause they received it, and with what fury and resolution they prosecuted their former desire, he was borne down with the stream, and, as it is probable, by the people’s instigation, built an altar to it.
To the Lord, Heb. to Jehovah; which title being peculiar to the true God, and being here given by Aaron to the calf, with the approbation of the people, makes it more than probable that the people designed to worship the true God in this calf, which they made only as a visible token of God’s presence with them, and an image by which they might convey their worship to God."