`Abdullah b. `Abbas reported: He spent (one night) in the house of the Messenger of Allah (ﷺ). He (the Holy Prophet) got up, brushed his teeth and performed ablution and said: "In the creation of the heavens and the earth, and the alternation of the night and the day, there are indeed signs for people of understanding" (al-Qur'an, iii. 190), to the end of the Surah. He then stood up and prayed two rak`ahs, standing, bowing and prostrating himself at length in them. Then he finished, went to sleep and snored. He did that three times, six rak`ahs altogether, each time cleaning his teeth, performing ablution, and reciting these verses. Then he observed three rak`ahs of Witr. The Mu'adhdhin then pronounced the Adhan and he went out for prayer and was saying: "O Allah! place light in my heart, light in my tongue, place light in my hearing, place light in my eyesight, place light behind me, and light in front of me, and place light above me, and light below me. O Allah! grant me light."