Sayyiduna Zirr bin Hubaish (may Allah be pleased with him) narrates that if there were not people of little understanding among you, I would have placed my hands on my ears and proclaimed loudly that Laylat al-Qadr is in the last seven nights of Ramadan; three nights before it and three nights after it. This information was given to me by a truthful man, that is, Ubayy bin Ka'b (may Allah be pleased with him), from the Messenger of Allah (peace and blessings be upon him).
Hadith Referenceالمنتقى ابن الجارود / كتاب الصيام / 406
Hadith Gradingغلام مصطفےٰ ظهير امن پوري:إسناده حسن
Hadith Takhrijاز غلام مصطفےٰ ظهير امن پوري:«إسناده حسن: زوائد مسند الإمام أحمد: 131/5، السنن الكبرى للنسائي: 11690، اس حدیث کو امام ابن خزیمہ رحمہ اللہ (2187) نے صحیح کہا ہے، یزید بن ابی سلیمان راوی "حسن الحدیث" ہے۔»