The Unparalleled King isn't truly a fool; it understands that if Li Xiu refuses to assist it, even with the Forbidden Light to protect him, it won't be able to keep Li Xiu.
Li Xiu's words were essentially providing it with a graceful exit; if relations between the two became strained, it would have no chance to escape its predicament.
"What do you want? I've already said, once I unify the world, you'll be above all others, whatever you desire will be yours, so why rush?" The Unparalleled King tried to entice Li Xiu with promises.
Li Xiu wasn't going to fall for it and replied calmly, "Then I thank Your Majesty in advance. But for now, I just want to know, what exactly is the origin of the Godslayer Shrine?"
The Unparalleled King pondered, "It's no harm telling you, that Godslayer Shrine is a Longevity Plaque from Longevity Island, with which you can obtain an Undying Body."
