It wasnarrated that Abu Sa'eed Al-Khudri said:
"We observed I'tikafwith the Messenger of Allah (ﷺ) during the middle ten days ofRamadan. He said: 'I have been shown Lailatul-Qadr, then I wascausedto forget it, so seek it in the last ten night, on theodd-numberednights.'" (FR)
English reference (FR): Vol. 1, Book 7, Hadith 1766 (FR)
Arabic reference (FR): Book 7, Hadith 1838 (FR)