It is not permissible to pray behind one who calls upon the dead for aid, for he is a polytheist committing major shirk

Question:
In his final question, he asks: What is the ruling in Islam regarding a man who has memorized the Book of Allah and is knowledgeable about it in terms of tajwid (rules of Qur'anic recitation), yet he circumambulates graves and follows the adherents of Sufi orders in various countries? Is it permissible to pray behind him if he comes to lead people in prayer? And what is the ruling on the prayer of the followers if they are content with that?

Answer:
One who attaches himself to graves, calls upon them for aid, and seeks blessing from them is a polytheist committing major shirk (associating partners with Allah). Therefore, his prayer is not valid, and it is not permissible for him to lead people in prayer until he repents to Allah (Glorified and Exalted is He). Yes.