Munyatul Musolli is a respected work in the Shafi'i school. It covers critical topics like invalidators of prayer, sutrah, and khushu'. If you are studying Shafi'i fiqh, the book itself is a 4/5 star classic.
It's important to clarify that (often fully titled Munyatul Musolli wa Ghunyatil Mubtadi' ) is a classical Shafi'i fiqh text focusing on the laws of prayer (salat), purification, and the etiquette of worshippers. The number "169" typically refers to a PDF page number or a specific edition's section, not a verse or hadith number. Kitab Munyatul Musolli Pdf 169
Student of Fiqh