Can you help me with a source?

So. There's a midrash that says that we had fallen to the 49th level of tum'ah in Egypt, and that had we fallen one level more, we never would have been able to be redeemed. And there's a midrash that says that during the 7 weeks between the Exodus and Matan Torah, we rose to the 49th level of bina. I don't know if the two are the same source.

I've been trying to find the source of these statements for many years. You see the idea mentioned all over the place. But it's never sourced. Seriously never.

A few years ago, a rav I exchanged some e-mails with told me that the source is in the Zohar Hadash, parashat Yitro. And sure enough, it's there, at the very beginning, albeit in Aramaic. But it seemed strange to me that the source should be in the Zohar Hadash. I mean, there are a lot of people who cite this midrash who would probably be appalled to find that the idea came from Kabbalah. Still, it's the only source I've ever seen.

This past Shabbat, I was speaking with an expert in Jewish textual analysis at shul. And he said the idea is definitely from the Gemara or midrash, and did not originate in the Zohar. Of course, he didn't have a particular source in mind. So I remain a little skeptical and a little puzzled.

Folks in the JBlogosphere tend to be fairly bright, so I thought I'd toss this out to y'all. Is there any source earlier than the Zohar Hadash for the idea that were down 49 levels of tum'ah in Egypt and up 49 levels of bina at Sinai?