Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates: We mentioned Laylat al-Qadr, and he (peace and blessings be upon him) said: "How much of the month has passed?" We said: Twenty-two days, and eight remain. He (peace and blessings be upon him) said: "Twenty-two have passed and seven remain. Seek it tonight; the month is twenty-nine (days)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8541