As an old mouse, passing out while injured basically spelled the end of any chance of survival.
He was very aware that he might never wake up again, perhaps to be injured in his sleep once again by someone in the village or by a cat, his cultivation destroyed in an instant, his soul returning to the Underworld.
Who would have known that upon opening his eyes, an elderly grandmother would be taking care of him.
They say that Gray Fairy had the ability to foresee the future, but it wasn't really that magical. Even if he attempted to foresee, he could only get a glimpse into one out of ten matters related to himself.
For example, he had a premonition that he would encounter a disaster, but whether he would survive that disaster was unknown.