"You and each of you do covenant and promise that you will pray and never cease to pray to Almighty God to avenge the blood of the prophets upon this nation, and that you will teach the same to your children and to your children's children unto the third and fourth generation."2
"The prophets" referred to Joseph Smith and Hyrum Smith, who were killed in 1844 by a mob while in jail in Carthage, Illinois. "This nation" referred to the United States.3
The oath entered the endowment at a time when many Mormons hoped for retribution for the deaths of Joseph and Hyrum.4 At least one member of the LDS First Presidency understood the oath to include a personal obligation that, "if he had ever met any of those who had taken a hand in that massacre he would undoubtedly have attempted to avenge the blood of the martyrs."5 However, other Mormons understood the oath to require only prayer for God's vengeance, and not any obligation to take vengeance personally.6
The prayer to which endowed Mormons obligated themselves took place, in at least some cases, as part of the Mormon prayer circle ceremony,7 which was also part of the Endowment, but was often performed separately.
Doctrinal basis
The idea that spilled blood "cries out" for retribution finds several examples in Mormon scripture. In the Bible, for example, the blood of Abel ascended to the ears of God after he was killed by Cain (Genesis 4:10). In the Book of Mormon, the "blood of a righteous man" (Gideon) was said to "come upon" the theocratic leader Alma "for vengeance" against the murderer (Nehor) (Alma 1:13). Mormon scripture also refers to the "cry" of the blood of the saints ascending from the ground up to the ears of God as a testimony against those who killed them (2 Ne. 26: 3; D&C 88:6).
According to Brigham Young, it was inevitable that Joseph Smith's blood, and the blood of all martyrs to the faith, would be "atoned for" in "His own due time".(Young 1853, p. 32) Their blood, he said, was "under the altar" and "crying to God, day and night, for vengeance".(Young 1853, p. 32)
Beginning in 1919, church presidentHeber J. Grant appointed a committee charged with revising the ceremony, which was done under the direction of ApostleGeorge F. Richards from 1921 to 1927. Richards revised the ceremony to eliminate the oath of vengeance.(Buerger 2002, pp. 139–40)
Because they were both removed from the endowment in the 20th century and both deal with blood doctrines, the oath of vengeance and the so-called "blood oaths" or "penalties" are often confused as being related teachings. While the blood oaths in the ceremony related to protecting the ritual's secrecy and the rejecting of promises given to the patron during the washing and anointing ordinances (Buerger 2002, p. 141), the oath of vengeance deals directly with praying to God for justice in regard to the deaths of Mormon leaders. The oath of vengeance is also frequently confused with the concept of blood atonement.
^Buerger (1987, p. 53), citing the example of Allen Stout, a former Danite, who upon seeing the coffins of Joseph and Hyrum, vowed that he "would never let an opportunity slip unimproved of avenging their blood.
Buerger, David John (2002), The Mysteries of Godliness: A History of Mormon Temple Worship (2nd ed.), Salt Lake City: Signature Books, ISBN 1560851767.
United States Senate (1906), Burrows, Julius Caesar; Foraker, Joseph Benson, eds., Proceedings Before the Committee on Privileges and Elections of the United States Senate in the Matter of the Protests Against the Right of Hon. Reed Smoot, a Senator from the State of Utah, to Hold His Seat, 4, Washington: Government Printing Office.
Young, Brigham (April 6, 1853), "Necessity of Building Temples—the Endowment", in Watt, G.D., Journal of Discourses by Brigham Young, President of the Church of Jesus Christ of Latter-Day Saints, His Two Counsellors, the Twelve Apostles, and Others, 2, Liverpool: F.D. & S.W. Richards, 1855, pp. 29–33.