What is the religious ruling regarding the dream of my friend, who sees in his sleep a black man preventing him from performing Fajr prayer, and a shaykh interpreted this to him as an infidel jinn that will only depart through a person far from Allah? And is what his grandmother did, finding a paper in his father's sofa to get rid of sorcery, and her dealing with shaykhs who visit her at night, considered Islamically permissible?

We have nothing that can be asserted definitively regarding the grandmother and those who heard her speaking, and Jinn assume the forms of humans and animals and speak to people. Some of them were seen by Abu Hurayrah and Ubayy ibn Ka'b, and Sheikh al-Islam Ibn Taymiyyah also mentioned that Jinn can appear in the forms of humans and animals. For treatment, consistently reciting Surat Al-Baqarah in the home and Ayatul-Kursi before sleep protects a Muslim from Satan. Furthermore, Ruqyah (definition) Shariah has a significant effect.