What is the ruling on going to soothsayers and believing them? And what is the authenticity of the Prophetic Hadith: "The prayer of one who goes to them and believes them is not accepted"? And what is the opinion of scholars on this?

Consulting soothsayers and believing them is forbidden due to the narrations from the Prophet (ﷺ) which prohibit approaching fortune-tellers and soothsayers, believing them, and threaten those who do so. Divination and dealing in it are also forbidden.

Whoever has been afflicted by such a thing must hasten to repent.

And Allah knows best.