Heitstrenging, also known as Hietstrenja, Heitstrengingar or Strengdir, was the Norse ritual of making solemn vows, particularly at Yule. The practice was eventually discarded when Christianity gained dominance in the region.
The vows were traditionally made while laying hands on the bristles of the sonargöltr, the boar sacrificed at the blót on the evening of Yule Eve, and in association with the Bragafull or chieftain's toast. According to some sagas, the speaker would stand and first place his foot upon a stone or bench, prefacing his vow with the words "I mount on the block and solemnly swear...".
The association with the sacrificial boar and the ritual toast gave the vows the force of an oath. However, due to the ritual process, they usually came after the speaker was drunk. They became a topos in the later sagas, often as a form of bragging and promising the performance of some great feat, and taking place not only at Yule but at other sacrificial feasts, weddings, arvals or just ordinary banquets. The vows were solemn and there were punishments for breaking them, but they were not always important. Harald Hairfair, the unifier of Norway, promised to not comb or cut his hair until he ruled the entire country. More often, though, they were regarded as a matter of great significance. In Jómsvíkinga saga, the compatriots of Sweyn Forkbeard vow to ravage Norway and kill Haakon Jarl, while making sure to rape Thorkill's daughter.
- "Sonargǫltr", Rudolf Simek, Dictionary of Northern Mythology, tr. Angela Hall, Cambridge: Brewer, 1993, repr. 2000, ISBN 978-0-85991-369-0, p. 298.
- Richard North, Heathen Gods in Old English Literature, Cambridge Studies in Anglo-Saxon England 22, Cambridge, 1997, ISBN 978-0-521-55183-0, p. 74.
- Jan de Vries, Altgermanische Religionsgeschichte, Volume 1, Grundriß der germanischen Philologie begründet von Hermann Paul 12/I, 2nd ed. Berlin: De Gruyter, 1956, repr. as 3rd ed. 1970, OCLC 747429, p. 504 (German)
- Mary Wilhelmine Williams, Social Scandinavia in the Viking Age, New York: Macmillan, 1920, OCLC 2618704, pp. 321–22.
- Charles Francis Keary, Norway and the Norwegians, New York: Scribner, 1892, OCLC 2651194, p. 174
- Rudolph Keyser, tr. M.R. Barnard, The Private Life of the Old Northmen London: Chapman and Hall, 1868, OCLC 2085285, p. 145.
- Michael Murphy, "Vows, Boasts and Taunts, and the Role of Women in Some Medieval Literature", English Studies 1985 (pdf)