On your life, my Lord King

What does “on your life” here mean?
Does it has the same meaning as “not on your life” or does it refer to something else?

“For though I have never been called a coward, I must plainly say that to meet that young man in battle is more than my heart would serve me for. And if (as is likely) his brother, the High King, is more dangerous than he—why, on your life, my Lord King, have nothing to do with him.”


It might be the author’s own version of the idiom ‘not on your life’, meaning ‘never, under no circumstance’.


I’m a little unsure of the meaning of ‘on your life’, but I think it’s closer to the opposite of ‘not on your life’. I think it’s more like a sign of sworn fealty. It’s placing the King’s life at utmost importance, with more value than anything else.

I have also seen ‘on my life’. I think it’s a way of swearing ‘on my life’. I think this is similar to other forms of swearing. For example:

Swearing on the Bible.
Swearing on your father’s name.
Swearing to be struck down if you are not telling the truth.

Or as kids we used to swear we are telling the truth:

Cross my heart and hope to die.
Stick a needle in my eye.


Another curious phrase from the land of Narnia, though it does have a medieval feel.
I would say something like “to safeguard your life”.