Wilford Woodruff reports Joseph teaching that the Father was a Savior on a previous earth like Jesus is for our earth.
Discourse, January 30, 1842, The Joseph Smith Papers website, accessed April 9, 2022
Jan 30[th] [1842] Joseph the Seer taught the following principles that the God & father of our Lord Jesus Christ was once the same as the Son or Holy Ghost bothaving [both having] redeemed a world became the eternal God of that world he had a son Jesus Christ who redeemed this earth the same as his father had a world which made them equal & the Holy Ghost would do the same in his turn & so would all the Saint
Marked as "unsourced" as, according to the Joseph Smith Papers website:
Wilford Woodruff copied this sermon into his booklet titled “Book of Revelations,” though his journal indicates Woodruff was away from Nauvoo on 30 January. Woodruff likely used someone else’s notes of the sermon when he recorded it. Except the brief note in JS’s journal, this is the only extant account of this sermon.