What is the ruling of Islamic law regarding a man who is semi-illiterate, rarely attends the Fajr and 'Isha prayers, yet steps forward to lead the other prayers without being asked, requests those who have memorized the Quran to establish the prayer so that he may lead it, and frequently recites Quranic verses in an inverted order?

A man's imamate (leadership of prayer) is valid if he does not violate its conditions and is knowledgeable of its correct form. His imamate is valid even if there is someone better than him. If the mosque has a resident Imam, he has precedence; otherwise, the most knowledgeable or best reciter among the people. It is advisable to gently advise the man and explain to him the seriousness of leading the prayer. As for praying with one's head lowered (tankees), it does not affect the validity of the prayer.