The Messenger of Allah ﷺ was reciting Surah Sad from the pulpit, and when he reached the verse of prostration, he descended and prostrated, and the people prostrated along with him.On another day, he recited it again, and when he reached the verse of prostration, the people prepared themselves to prostrate. The Prophet ﷺ said, "This is only the Tawba of a prophet, but I saw you readying yourselves to prostrate." So he came down and prostrated, and they prostrated with him.
قرأ رسول الله ﷺ وهوعلى المنبر {ص}، فلما بلغ السجدة نزل، فسجد، وسجد الناس معه، فلما كان يوم آخر قرأها، فلما بلغ السجدة تشزن الناس للسجود، فقال النبي ﷺ: إنما هي توبة نبي، ولكني رأيتكم تشرنتم للسجود. فنزل فسجد وسجدوا.
Abu Dawud (1410) narrated it, and Ibn Khuzayma (1455), Ibn Hibban (2765), and Hakim (2/431–433) graded it sahih, all of them through the route of Saeed bin Abu Hilal, from Iyad bin Abdullah bin Saad bin Abu Sarh, from Abu Saeed, who then related it.Its isnad is hasan because of Saeed bin Abu Hilal, for he is one whose hadith is hasan. Hakim said, "Sahih according to the standard of the two Shaikhs." Nawawi said in al-Khulasa (2140), "Its chain is sahih according to the standard of Bukhari."