“It features al-Qasim ibn Maʿn, and I have found no one who recorded his biography.” This is clearly a slip of the pen, for al-Qasim is a trustworthy, distinguished transmitter cited by Abu Dawud and al-Nasaʾi. Most likely the author meant to write “Muʿammar ibn Sahl” but accidentally wrote “al-Qasim ibn Maʿn”; Allah knows best. I have since located a favorable entry for Muʿammar ibn Sahl in Ibn Hibban’s al-Thiqat, 9/196 (India ed.), which states: “Muʿammar ibn Sahl ibn Muʿammar al-Ahwazi, a precise shaykh who relates uncommon reports.” The only person who narrates from him is Muhammad ibn Mahmuwayh al-Jawhari—one of the well-known, prolific transmitters—who related nearly twenty hadiths from him (nos. 7325–7343 in my numbering). 1 The hadith is reported by al-Bukhari 4/232, 7/89, 9/95, 190–192; al-Nasaʾi 2/93; Ibn Saʿd 3/2/77; al-Bayhaqi 7/258; and Ahmad 3/165, 190, 204, 226, 271.