Hazrat Uqbah bin Amir Juhani says that I was with the Holy Prophet (peace and blessings be upon him) on a journey. When dawn broke, he gave the call to prayer (adhan) and the iqamah, then made me stand on his right side, and then recited the Mu'awwidhatayn (Surah Al-Falaq and Surah An-Naas). When he finished the prayer, he said, "What is your opinion?" I replied, "I have the correct opinion." He said, "When you go to sleep, recite these Surahs, and when you wake up, also recite these Surahs."