You know what it looks like… but what is it called?
TAKE THE QUIZ“swear on”
The following 2 entries include the term swear on.
swear on one's mother's grave
idiom—used to stress that one is being absolutely honest
swear on the Bible
idiom: to put a hand on the Bible and make a formal promise to tell the truth
Love words? Need even more definitions?
Merriam-Webster unabridged