beswear

Etymology
From.

Verb

 * 1)  To swear by; swear about or regarding; swear at or to; promise
 * 2) * 1888, Teutonic mythology, Jacob Grimm, James Steven Stallybrass, tr. by J.S. Stallybrass - Volume 4:
 * Some masters of the art take a pure child and set him in their lap, then lift his hand up and let him look into his nail, and beswear the child and the nail with a great adjuration, and then speak in the child's ear three unknown words, whereof one is Oriel, the others I withhold for fear of offending.
 * 1) * 1895, The Saga Library:
 * Thereupon they met themselves, and then peace was talked over, and this was the matter agreed on, that the kings beswore each other brotherhood and settled peace between them while they should both be alive; [...]