What is the takhrij of the hadith: "Lay down the inkwell, set up the ya (ي), separate the sin (س), do not blind the mim (م), beautify Allah (الله), lengthen the Most Gracious (الرحمن), and make good the Most Merciful (الرحيم); and place your pen on your left ear, for that is more conducive to memory for you," and in which hadith books is it found?

This tradition, narrated from Mu'awiyah (may Allah be pleased with him), contains written injunctions from the Prophet (peace be upon him) to Mu'awiyah, such as: "Dip the inkwell, slant the pen, straighten the 'ba', separate the 'sin', do not obscure the 'mim', beautify 'Allah', lengthen 'Ar-Rahman', and perfect 'Ar-Rahim', and place your pen on your left ear, for it will be more mindful for you." This was mentioned by the author of Al-Firdaws bi-Ma'thur al-Khitab and the author of Adab al-Imla' wal-Istila', but it has not been authenticated by a recognized Imam of Hadith (definition).