And we know not whether evil is intended for those on earth, or whether their Lord intends for them guidance.
meaning, `we do not know if this -- the matter which has occurred in the sky -- is intended for those who are in the earth or if their Lord intends some guidance for them.'
They stated this in such a manner out of their etiquette in phrasing their speech, because they did not attribute the doing of evil to anyone and they attributed the good to Allah.
Verily, it has been recorded in the Sahih,
وَالشَّرُّ لَيْسَ إِلَيْك
And evil is not attributed to You (Allah).
It used to be that shooting stars (meteors) occurred before this, however it did not happen much, rather only occasionally. As was reported in the Hadith of Ibn `Abbas when he said,
"While we were sitting with the Messenger of Allah a shooting star flashed in the sky. So the Prophet said,
مَا كُنْتُمْ تَقُولُونَ فِي هَذَا
What did you all used to say about this?
We replied, "We used to say that a great person has been born and a great person has died."
The Prophet said,
لَيْسَ كَذَلِكَ وَلَكِنَّ اللهَ إِذَا قَضَى الاَْمْرَ فِي السَّمَاء
This is not so, rather whenever Allah decrees a matter in the heaven..."
and then he went on to narrate the rest of the Hadith which we have already mentioned in its entirety in Surah Saba'.
This is what caused them to seek the reason for this occurrence. So they set out searching in the east and the west. Then they found the Messenger of Allah reciting (the Qur'an) while leading his Companions in prayer. Thus, they knew that this Qur'an was the reason for the sky being guarded. Therefore, some among them believed in it and the others became more rebellious in their transgression. A discussion of this has preceded in a Hadith of Ibn `Abbas concerning Allah's statement in Surah Al-Ahqaf,
وَإِذْ صَرَفْنَأ إِلَيْكَ نَفَراً مِّنَ الْجِنِّ يَسْتَمِعُونَ الْقُرْءَانَ
And (remember) when We sent towards you (Muhammad) a group of the Jinn (quietly) listening to the Qur'an. (46;29)
There is no doubt that when so many shooting stars began appearing in the sky, it horrified humans and Jinns alike. They were very disturbed and alarmed by it. They thought that it was the destruction of the world.
As-Suddi said,
"The sky was never guarded except if there was a Prophet in the earth or the religion of Allah was victorious and dominant in the earth."
So the devils before the time of Muhammad had taken sitting stations for themselves in the heaven of this world and they would listen to the matters that occurred in the heaven. But when Allah sent Muhammad as a Prophet and Messenger, they were suddenly pelted one night (with the flaming, shooting stars). So the people of Ta'if were frightened because of this and they began to say,
`The dwellers of the sky have been destroyed.'
This was because they saw the severe fires in the sky and the shooting flames. They began freeing their servants and abandoning their luxuries. So `Abd Yalayl bin `Amr bin `Umayr said to them and he was referred to for judgement among them
"Woe to you O people of Ta'if! Hold on to your wealth and look at these guiding stars in the sky. If you see them remaining in their place, then the dwellers of the sky have not been destroyed, rather this has happened because of Ibn Abi Kabshah (-- meaning Muhammad). And if you look and see that you can no longer see these stars, then verily the dwellers of the sky have been destroyed."
So, they looked and saw that the stars still remained, and thus, they kept their wealth. The devils also were frightened during that night. They went to Iblis and informed him of what happened to them. So he (Iblis) said,
"Bring me a handful of dirt from every land so that I may smell it."
So they brought it and he smelled it and said, "It is your friend in Makkah."
Then he sent a group of seven Jinns to Makkah, and they found the Prophet of Allah standing in prayer in Al-Masjid Al-Haram while reciting the Qur'an. They drew near to him eager to hear the Qur'an, until their chests almost pressed against him. Then they accepted Islam and Allah revealed their matter to His Messenger .
We have mentioned this chapter in its entirety in the first section of the Kitab As-Sirah with lengthy discussion. Allah knows best and unto Him is all praise and blessings