Sahih Muslim
Pertaining To The Charateristics Of The Hypocrites And Command Concerning Them (Kitab Sifat Al-Munafiqin Wa Ahkamihim)
Book Number: 038 / Hadith Number: 6697
Ibn Umar reported Allah's Apostle (may peace be upon him) saying like this but with this change of words:" She sometimes finds a way in one flock and then in another flock."