Passage 1:Passage 2:
"He is not easy to describe. There is something wrong with his appearance; something displeasing, something down-right detestable. I never saw a man I so disliked, and yet I scarce know why. He must be deformed somewhere; he gives a strong feeling of deformity, although I couldn’t specify the point. He’s an extraordinary looking man, and yet I really can name nothing out of the way.”

–The Strange Case of Dr. Jekyll and Mr. Hyde,
Robert Louis Stevenson

How do the two passages develop the theme "It is important to trust your instinct”?

The first passage explains what it means to have a gut instinct; the second gives an example.
The first passage introduces the idea that people have bad feelings from Hyde; the second passage reinforces that idea.
Both passages discuss what happens when people do not trust their instincts.
Both passages give an example to show how important it is to have faith in others.