The Messenger of Allah ﷺ taught him fifteen prostrations in the Quran, three of which are in the Mufassal section, and two in Surah al-Hajj.
حدثنا محمد بن عبد الرحيم بن البرقي حدثنا ابن أبي مريم أخبرنا نافع بن يزيد عن الحارث بن سعيد العتقي عن عبد الله بن منين من بني عبد كلال
أن رسول الله ﷺ أقرأه خمس عشرة سجدة في القرآن منها ثلاث في المفصل وفي سورة الحج سجدتان
[Its chain is daif] Ibn Majah reported it in "Establishing Prayers," chapter on the number of prostrations of the Quran, hadith 1057, from the hadith of Ibn Abu Maryam, with this wording.Harith bin Saeed is of unknown status, and I did not find any reliable verification of his reliability. The hadith has a daif corroborating narration in Tirmidhi, hadith 568, 569, and Ibn Majah, hadith 1055.