What is the authenticity of the hadith: "Whoever comes to a soothsayer or a diviner has disbelieved in the nation of our master Muhammad," and how can this be reconciled with the Prophet's teaching of the Qur'an to the Muslim jinn, and what is the ruling on going to soothsayers and diviners, and what are the methods of treatment to get rid of envy, sorcery, possession, and sadness?

There is no hadith with this exact wording. However, it is authentically reported from the Prophet, peace and blessings be upon him: "Whoever comes to a soothsayer and believes what he says has disbelieved in what was revealed to Muhammad, peace and blessings be upon him." The Prophet's teaching of the Muslim jinn is not soothsaying; rather, it is an endeavor to guide his nation, as Allah sent him to both jinn and humans.