Mas’ala 1662الأمShafi'ivol. 1, p. 205vol. 1, p. 205 ائْتِمَامُ الرَّجُلَيْنِ أَحَدُهُمَا بِالْآخَرِ وَشَكُّهُمَا Read the whole chapterCopy with source On the map: PrayerCompare