Joseph's Journal entry for May 4, 1842 describing first endowment ceremony.
Joseph Smith, Journal, December 1841–December 1842, 94, The Joseph Smith Papers website, accessed June 14, 2022
Wednesday 4 In council in the Presidents & General offices with Judge [James] Adams. Hyram [Hyrum] Smith Newel K. Whitney. William Marks, Wm Law. George Miller. Brigham Young. Heber C. Kimball & Willard Richards. [illegible] & giving certain instructions concerning the priesthood. [illegible] &c on the Aronic Priesthood to the first [illegible] continueing through the day.