Sahih Muslim
The Book of Fasting (Kitab Al-Sawm)
Book Number: 006 / Hadith Number: 2632
'A'isha (Allah be pleased with her) and Ibn Numair reported Allah's Mes- senger (may peace be upon him) as saying: Look for (and in the words of Waki, seek) Lailat-ul-Qadr in the last ten nights of Ramadan.