"I.... give up."
You don't know anyway to get out of this. It means losing the books, but at least you'll get to live.
"That's a smart idea. Now, just set both books on the ground, and back away from them."
You set the books down, and back away. The man goes and picks both of them up.
"Well then, that was a lot easier than I had hoped for."
He then proceeds to flip through each of the books, reading the spells.
"Aha hmmmm."
Suddenly he points at you, he's preparing to cast a spell.
"Hey I gave you the books! I thought you said you'd let me live!"
"Oh I will." He replies. "I'm just going to make sure you don't interfere after this."