From Sahih Muslim (Hadith 2768):
Abu Huraira (Allah be pleased with him) reported Allah's Messenger (ﷺ) as saying:I was shown Lailat-ul-Qadr; then some members of my family awoke me up, then I was caused to forget it. So seek it in the last week. Harmala said: (The Prophet did not say:" I was made to forget," but he stated):" But I forgot it
Reference: Muslim 2768