Devarim 4:15 states:
Take ye therefore good heed unto yourselves—for ye saw no manner of form on the day that the LORD spoke unto you in Horeb out of the midst of the fire—
And also in Shemos 19:11:
and be ready against the third day; for the third day the LORD will come down in the sight of all the people upon mount Sinai.
Does this necessarily mean that the Israelites perception of G-d was one that was formless, or could it just mean that it was obscured/they weren't privy to it, and thus cannot make any sort of image/idol since they have no idea how he looked.
It also says in the Midrash/Talmud somewhere that G-d appeared as an elder at sinai, is that somehow contradictory to this pasuk or is it within the confines of it's interpretation?
Note the Rambam and other midrashic works I've seen use this as proof that G-d is incorporeal.