The last 3 Qul's are the strongest protection against envy, evil eye, magic and jinn. It is Sunnah to read them three times in the morning and evening, three times before going to sleep, once after every Salah, and when one is ill.
 
Ibn al-Qayyim (rahimahullah) wrote: ‘These Surahs are extremely effective in repelling magic, evil eye, and the rest of the evils. The need for a slave to seek Allah’s protection with these Surahs is greater than his need for eating, drinking and clothes.’
 
The following Hadith's demonstrate the importance the Messenger of Allah ﷺ would give to the 3 Qul's:
 
Best Ruqyah
‘Aishah RA narrated: Whenever the Messenger of Allah ﷺ would become sick, he would recite [the last 3 Surahs of the Quran] and then blow over his body. She says: “During his last illness from which he passed away, the Messenger of Allah ﷺ used to blow over himself. But when his sickness intensified, I used to (recite and then) blow over him using his own hands because of their blessings.” (Bukhari)
 
In another hadith, she mentions that whenever anyone from his family would become ill, He ﷺ would blow over them with these three Surahs. (Muslim)
 
Best Protection
Surah Nas and Surah Falaq are the best protection against envy, evil eye and the shayatin. This can be seen in the following hadīth:
Anas RA said: “The Messenger of Allah ﷺ used to seek refuge in Allah from the jinn and the human evil eye until the Mu’awwidhatayn were revealed. When they were revealed, he adopted them and abandoned everything else.” (Tirmidhi)
The Messenger of Allah ﷺ said: “No seeker has sought protection with anything like them.” (Abu Dawud)
‘Uqbah RA reported that the Messenger of Allah ﷺ said: “Shall I inform you of the best words with which you can seek Allah’s protection?” I said: “Yes.” He ﷺ said: “Surah Falaq and Surah Nas.” (Ahmad)
 
Morning and Evening
The Messenger of Allah ﷺ said: “Recite Surah Ikhlas and Mu’awwidhatayn (Surah Falaq and Surah Nas) three times in the morning and the evening. It will suffice you in all respects.” (Tirmidhi)
 
Before Sleeping
‘Aishah RA narrated that when the Messenger of Allah ﷺ retired to bed every night, he would hold his hands together and then blow into them. He would recite [Surah Ikhlas, Surah Falaq and Surah Nas) ] into them. Then he would wipe them over whatever he could of his body, starting with his head and face and the front of his body, and he would do that three times. (Bukhari)