Giuliani literally said on Fox News. Watch the actual video, don't just complain about media bias. The evidence is right there in the linked article.

“I'll tell you the whole history of it,” Giuliani responded eagerly. “So when [Trump] first announced it, he said, 'Muslim ban.' He called me up. He said, 'Put a commission together. Show me the right way to do it legally.' "

Better source for you?