It is narrated from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) was reciting Surah Sad on the pulpit. When he (peace and blessings be upon him) reached the place of prostration, he came down from the pulpit and prostrated, and the people prostrated along with him (peace and blessings be upon him). Then on another day he (peace and blessings be upon him) recited it again, and when he reached the verse of prostration, the people got ready to prostrate. Upon this the Messenger of Allah (peace and blessings be upon him) said: "This is the repentance of a prophet (Sayyiduna Dawud, peace be upon him), but I saw that you have got ready to prostrate." Then he (peace and blessings be upon him) came down and prostrated, and the people also prostrated along with him (peace and blessings be upon him). This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.