Allah says,

﴿وَأَنَّهُ كَانَ رِجَالٌ مِّنَ الإِنسِ يَعُوذُونَ بِرِجَالٍ مِّنَ الْجِنِّ فَزَادوهُمْ رَهَقاً ﴾

(And verily, there were men among mankind who took shelter with the males among the Jinn, but they increased them in Rahaq.) meaning, `we used to think that we had some virtuous status over mankind because they used to seek refuge with us whenever they (men) would settle in a valley or any place in the wilderness, the open country steppes and other places.' This was the custom of the Arabs in the pre-Islamic days of ignorance. They used to seek refuge with the greatest Jinn of a particular place so that no harm or evil would afflict them. Like one would do if he entered into the land of his enemies, in the vicinity of a great and powerful man, he would seek the protection and guardianship of that man. So when the Jinns saw that the humans were seeking refuge with them due to their fear of them, they increased them in Rahaq which means fear, terror and fright. They did this so that the people would be more afraid of them and seek refuge with them even more. As Qatadah said concerning this Ayah,

﴿فَزَادوهُمْ رَهَقاً﴾

(but they increased them in Rahaq.) means, "the Jinns were courageous and increased in insolence against them.'' As-Suddi said, "A man used to set out with his family (on a journey) until he came to a piece of land where he would settle. Then he would say, `I seek refuge with the master (Jinn) of this valley from the Jinns, or that myself, my wealth, my child or my animals are harmed in it.''' Qatadah said, "When they sought refuge with them instead of Allah, the Jinns would overcome them with harm because of that.'' Ibn Abi Hatim recorded from `Ikrimah that he said, "The Jinns used to fear humans just like humans fear them, or even worse. So whenever humans would come to a valley the Jinns would flee. So the leader of the people would say, `We seek refuge with the leader of the inhabitants of this valley.' So the Jinns said, `We see these people fleeing from us just like we flee from them.' Thus, the Jinns started coming near the humans and afflicting them with insanity and madness.'' Thus, Allah said,

﴿وَأَنَّهُ كَانَ رِجَالٌ مِّنَ الإِنسِ يَعُوذُونَ بِرِجَالٍ مِّنَ الْجِنِّ فَزَادوهُمْ رَهَقاً ﴾

(And verily, there were men among mankind who took shelter with the males among the Jinn, but they increased them in Rahaq.) meaning, in sin. Abu `Aliyah, Ar-Rabi` and Zayd bin Aslam, all said,

﴿رَهَقاً﴾

(in Rahaq) "This means in fear.'' Mujahid said, "The disbelievers would increase in transgression.'' Concerning Allah's statement,

﴿وَأَنَّهُمْ ظَنُّواْ كَمَا ظَنَنتُمْ أَن لَّن يَبْعَثَ اللَّهُ أَحَداً ﴾

(And they thought as you thought,) means, "the Jinns were courageous and increased in insolence against them.'' As-Suddi said, "A man used to set out with his family (on a journey) until he came to a piece of land where he would settle. Then he would say, `I seek refuge with the master (Jinn) of this valley from the Jinns, or that myself, my wealth, my child or my animals are harmed in it.''' Qatadah said, "When they sought refuge with them instead of Allah, the Jinns would overcome them with harm because of that.'' Ibn Abi Hatim recorded from `Ikrimah that he said, "The Jinns used to fear humans just like humans fear them, or even worse. So whenever humans would come to a valley the Jinns would flee. So the leader of the people would say, `We seek refuge with the leader of the inhabitants of this valley.' So the Jinns said, `We see these people fleeing from us just like we flee from them.' Thus, the Jinns started coming near the humans and afflicting them with insanity and madness.'' Thus, Allah said,

﴿وَأَنَّهُ كَانَ رِجَالٌ مِّنَ الإِنسِ يَعُوذُونَ بِرِجَالٍ مِّنَ الْجِنِّ فَزَادوهُمْ رَهَقاً ﴾

(And verily, there were men among mankind who took shelter with the males among the Jinn, but they increased them in Rahaq.) meaning, in sin. Abu `Aliyah, Ar-Rabi` and Zayd bin Aslam, all said,

﴿رَهَقاً﴾

(in Rahaq) "This means in fear.'' Mujahid said, "The disbelievers would increase in transgression.'' Concerning Allah's statement,

﴿وَأَنَّهُمْ ظَنُّواْ كَمَا ظَنَنتُمْ أَن لَّن يَبْعَثَ اللَّهُ أَحَداً ﴾

(And they thought as you thought, that Allah will not send any Messenger.) meaning, Allah would never send a Messenger after this long period of time. This was said by Al-Kalbi and Ibn Jarir.

﴿وَأَنَّا لَمَسْنَا السَّمَآءَ فَوَجَدْنَـهَا مُلِئَتْ حَرَساً شَدِيداً وَشُهُباً - وَأَنَّا كُنَّا نَقْعُدُ مِنْهَا مَقَـعِدَ لِلسَّمْعِ فَمَن يَسْتَمِعِ الاٌّنَ يَجِدْ لَهُ شِهَاباً رَّصَداً - وَأَنَّا لاَ نَدْرِى أَشَرٌّ أُرِيدَ بِمَن فِى الاٌّرْضِ أَمْ أَرَادَ بِهِمْ رَبُّهُمْ رَشَداً ﴾

(8. `And we have sought to reach the heaven; but we found it filled with stern guards and flaming fires.') (9. `And verily, we used to sit there in stations, to (steal) a hearing, but any who listens now will find a flaming fire watching him in ambush.') (10. `And we know not whether evil is intended for those on the earth, or whether their Lord intends for them guidance.')