What is "oathing"

Usage examples of "oathing".

But he could not, for Jofre had passed the first oathing four seasons ago and Brother could not shed the blood of Brother.

Too many times had the Brothers on oathing been used by warring lords to put down rebellions or reduce some threat from the commoners.

This would be no oathing ceremony, for oathing had been closed to him—except the oathing to himself, his inner need.

Issha were not bond-worthy except by oath, and certainly no oathing had passed here.

I have heard of this oathing of your people, that you cannot break such a bond once it is taken.