Mishkat al-Masabih #2066

‘Abdullah b. Khubaib said: We went out one rainy and intensely dark night to look for God’s messenger, and when we caught up on him he said to me, “Say.” I asked him what I was to say, and he replied, “If you recite ‘Say, He is God, One’ and al-Mu'awidhatān (The last 3 sūras of the Qur’ān) three times morning and evening, they will serve you for every purpose.” Tirmidhī, Abū Dāwūd and Nasā’i transmitted it.