“Rasulullah (sal Allahu alaihi wa sallam) used to seek refuge from the jinn as well as from the evil eye until Surah al-Falaq and an-Naas were revealed. When they were sent down, he utilised them and left other things.” [Tirmidhi]
This hadith affirms the reality of the harm that can befall an individual from the envious, jealous gaze of a person who when he/she looks at you does not wish well for you. After the revelation of these two surahs, the Prophet (sal Allahu alaihi wa sallam) sought refuge with Allah (subhana wa ta’ala) against the evil of the envious person, the evil of magic and all other evil, by using these surahs. Regarding Surah al-Falaq and an-Naas, Rasul Allah (sal Allahu alaihi wa sallam) said that these are ayaat “the likes of which have never been seen before.” [Sahih Muslim]
Aisha (radi Allahu anha) reported that when the Prophet (sal Allahu alaihi wa sallam) went to bed every night, he used to cup his hands together and blow over them after reciting Surah Al-Ikhlas, Surah Al-Falaq and Surah An-Nas, and then rub his hands over whatever parts of his body he was able to rub, starting with his head, face and front of his body. He used to do that three times. When he became seriously ill, she used to recite (these two Surahs) and rub his hands over his body hoping for its blessings. [Sahih Bukhari]
These two surahs are the best to seek Allah’s protection with. Uqbah ibn Amir (radi Allahu anhu) reported that the Messenger of Allah (sal Allahu alaihi wa sallam) said: “No seeker of refuge can seek refuge with anything like these two.” [Abu Dawud] And he (sal Allahu alaihi wa sallam) said: “O Uqba, learn to recite Surah al-Falaq, for you will never recite a surah more cherished by Allah and more profound in His sight than this surah.” [Hakim, Dhahabi]
Both of these surahs as well as surah al-Ikhlas, to be recited three times each, are included in the morning and evening supplications/duas.