Imam al-Kisa’ee (one of the 7 Qurra’) relates: ‘I lead Haroon al-Rashid [the amir of the muslims] in prayer one day and he took a liking to my recitation. But then I made a mistake that not even a child makes! I wanted to say, ولعلهم يرجعون ‘… So that they may return’ But instead I said, ولعلهم يرجعين ‘… So that they (she) may return’ – [In other words, he mixed up the verb indicating a single fem. subject rather than the masc. plural] He said, ‘By Allah, Haroon didn’t have the boldness to say ‘You have made a mistake,’ but when I finished the prayer he asked me, ‘O Kisa’ee, what language/Qira’ah is this?’ I said, ‘O leader of the faithful, even the fine horses stumble at times.’ He said, ‘Yes, this is true.’ http://fajr.wordpress.com/category/seeking-knowledge-ilm/