Wilford Woodruff records in his journal that he proved Adam was Michael, the Ancient of Days, and the Father of all during a meeting with other Church leaders.
Wilford Woodruff, Journal, October 15, 1870, MS 1352, Church History Library
I dug potatoes in the forenoon & attended the school of the prophets in the Afternoon. Presidet Young asked me to speak upon the Character of Adam who he was. I proved that Adam was Michael the Arkangel, the Seventh Angel, & the Ancient of Days, The Father of all, & the prince of All. I quoted the 7 Chapter of Daniel 9 to 14 verse, Doctrin & Covenants 79 page 28 Paragraph 106 Page 35 P. 201 P. 2d Paragraph. I was followed by G Q. Cannon Presidt Young & G. A Smith.