Ma'ād al-Mu'izz, the caliph of Egypt, commissioned the invention of a fountain pen in 953 to avoid staining his hands and clothes.
While the question asks who invented the fountain pen "for Muslims," it's important to clarify that the invention wasn't exclusive to Muslims. Rather, it was commissioned by a Muslim ruler for his personal use. The historical records, specifically those by Qadi al-Nu'man al-Tamimi, indicate that Ma'ād al-Mu'izz requested a pen that held ink internally and wouldn't leak, leading to the creation of an early fountain pen prototype.
Therefore, while the exact inventor is not explicitly named in the readily available historical context, we know it was someone who created a pen to fulfill the specific requirements of the Caliph Ma'ād al-Mu'izz.
