Oath-taking is serious business in the Heathen community, and approached in a respected and straightforward manner. It is an act of dedication, often in combination with physical action, to solidify a community and a persons relationship with the Gods. So lets break this down.
The Meaning of an Oath
Gundarsson proposes two main different definitions for the word oath. An oath can be an avowal that something is true this is referred to as an assertory oath. An example of this includes Norse legal practices that were documented where individuals gave an oath to assert a defendants guilt or innocence, swearing that the oath was true. The other type of oath is a promissory oath, which is essentially a promise that something will be made true (Gundarsson, 2007). An example of this type of oath includes some tribalistic heathen sects where free folk swear hold-oaths of loyalty to their lord, or where a swearer will specific they will accomplish a specific deed. This is the oath most commonly seen in Heathenry, sworn at rites of profession, dedication, during sumbels and blots, and at other times.
Fealty oaths are not as common, though are still seen in some sects of Heathenry. Some branches require that every member of a tribe swear loyalty to one leader, of chieftain. Allegiance or loyalty oaths may imply fidelity to the state or kindred as a whole. Credal oaths include the religious affirmation of belief or certain tenets of faith (Lafayllve, 2013).
The Point of an Oath
What is the purpose of an oath, then? One explanation on oathing states In  Heathen belief, a true oath is a statement whose implications and essence have actually been laid out in the Well of Wyrd, becoming an integral part of orlog By laying the oath in the Well, the deed done in fulfillment of ones oath should fall into the Well and become part of orlay. In this way, one ensures that ones life has meaning and significance, and that ones deeds  form a permanent part of the fabric of reality (Hodge, 1997).
Some oaths are taken as a pledge to follow the ways of our ancestors and to be loyal to the Gods, as well as our kin. These types of oaths can be professions and dedications for new Heathens that have been accepted within their kindreds. They are highly personal, and as such will vary in length, content, and complexity. An example is:
I give this oath to all the Aesir and Vanir; I swear by blood and soil. I am a Heathen. I will follow the ways of my ancestors for the rest of my days. I will uphold the honor of my Folk and teach our ways to my children (Wodens Folk Kindred).
Other oaths are taken to dedicate a person to the service of a particular God or Goddess. This is commonly seen in lore. It may involve the taking on of a new name (as some may call themselves sons and dottirs of a deity, for example). It may also involve taking on a greater duty or fostering the cult of that specific deity.
When and Where to Oath
Oaths may be taken in private or in front of ones community. Oaths are commonly sworn at blots and sumbels. Most heathen belief holds that the seriousness of a commitment was measured by the degree of publicity attending it. Promises made in private [are] regarded as having little worth [when] compared to those before witnesses (Lafayllve, 2013 ). For many heathens, taking an oath not only binds the person who speaks it but it is also binding to those who witness it. As Lafayllve says, by their presence and their willingness to hear the oath, they are bound to see it take a positive outcome. While the person who swore the oath is solely responsible for seeing it to fruition, those who bear witness are also responsible to encourage and aid their kin.
Oaths and Community
A common practice among Heathens is the use of an oath to create formal bonds within their community. The formation of a kindred, for example, is usually accompanied by the adoption of law and taking of oaths intended to create a bond similar to the sworn-brotherhood oaths that are found throughout the sagas (Wodens Folk Kindred). It is not a requirement to oath when joining a kindred, or becoming a Heathen, and a person should never feel pressured into doing so.
Whether or not a person fulfills their oath plays a role in determining the reputation of a person, or how they are perceived within the community. Those who fulfill their oaths were seen to carry greater reputations than those who frequently failed to do so, a they were often not allowed to take further oaths. To oath was and is seen as serious business. Failure to meet a sworn oath can directly impact ones wyrd.
Swearing on Blade, Stone, and the Divine
Oaths were commonly sworn while grasping an oath-ring, a sword, a stone, or other such items. It seemed a common Norse folk belief that an oath made on earth-fast stone was binding in effect (Gundarsson, 2007). Some sources state that Danish kings stood on earth-fast stones during their coronations. Oaths could be sworn on nearly anything available. Some instances in the literature reveal examples where oaths were sworn upon a boar at a Yule feast, on the waves of a river in Hel, on ones weapons or horse, on ones land or wealth, and any other thing which was of value to the person swearing.
Deities were often called upon to witness oaths. Var, one of Friggs handmaidens, is said to be the keeper of oaths. In Gylfaginning, it mentions that Var listens to the oaths of men and takes revenge upon those who would break their vows. In parts of Iceland, it was not uncommon for oaths to be sworn by Freyr, Njordr, and the all-might As. In more modern heathenry, Tyr and Forseti (and sometimes Thor) are the deities most often called upon to bear witness to oathing. Invoking a deity as you swear an oath is seen as a serious ordeal: it is implied that if you fail to fulfill an oath you swore by a deity, you face the potential wrath of that deity or at the very least a falling out from their favor.
Some individuals take physical actions during oathing to make it visibly apparent what they are swearing by. It is not uncommonly for a person who makes an oath to make a visible mark on their body. A common historical trend in visible oathing involved vowing to not cut or trim ones hair until an oath was complete (Gundarsson, 2007). Examples include Vali refusing to trim his hair until Baldr had been avenged. A famous king in Norway vowed to not trim his hair until all of Norway was under his rule. This doesnt seem to be a common trend in modern heathenry, but other visible marks of oathing have taken its place. A person may choose to wear a token, a piece of jewelry, get a tattoo, cut into their flesh, etc.
- A Practical Heathen's Guide to Asatru By Patricia M. Lafayllve, 2013
- Our Troth: Living the Troth by Kvedulf Gundarsson, 2007
- Heathen Handbook by Wodens Folk Kindred