Indeed, they planned their plot, and their plot was with Allah, though their plot was not such as to remove the mountains from their places.
Shu`bah narrated that Abu Ishaq said that Abdur-Rahman bin Dabil said that Ali bin Abi Talib commented on Allah's statement,
وَإِن كَانَ مَكْرُهُمْ لِتَزُولَ مِنْهُ الْجِبَالُ
(though their plot was not such as to remove the mountains from their places),
"He who disputed with Ibrahim about his Lord, took two eaglets and raised them until they became adult eagles. Then he tied each eagle's leg to a wooden box with ropes and left them go hungry. He and another man sat inside the wooden box and raised a staff with a piece of meat on its tip. So, the two eagles started flying. The king asked his companion to tell him what he was seeing, and he described the scenes to him, until he said that he saw the earth as a fly. So, the king brought the staff closer to the eagles and they started landing slowly. This is why Allah said,
وَإِن كَانَ مَكْرُهُمْ لِتَزُولَ مِنْهُ الْجِبَالُ
`though their plot was hardly one to remove the mountains from their places."'
Mujahid also mentioned that;
this story was about Nebuchadnezzar, and that when the king's sight was far away from earth and its people, he was called, `O tyrant one! Where are you headed to!' He became afraid and brought the staff closer to the eagles, which flew faster with such haste that the mountains almost shook from the noise they made. The mountains were almost moved from their places, so Allah said,
وَإِن كَانَ مَكْرُهُمْ لِتَزُولَ مِنْهُ الْجِبَالُ
(though their plot was not such as to remove the mountains from their places)."
Ibn Jurayj narrated that Mujahid recited this Ayah in a way that means,
"though their plot was such as to remove the mountains from their places."
However, Al-Awfi reported that Ibn Abbas said that,
وَإِن كَانَ مَكْرُهُمْ لِتَزُولَ مِنْهُ الْجِبَالُ
(though their plot was not such as to remove the mountains from their places),
indicates that their plot was not such as to remove the mountains from their places.
Similar was said by Al-Hasan Al-Basri.
Ibn Jarir reasoned that,
"Associating others with Allah and disbelieving in Him, which they brought upon themselves, did not bother the mountains nor other creatures. Rather, the harm of their actions came to haunt them."
I (Ibn Kathir) said, this meaning is similar to Allah's statement,
وَلَا تَمْشِ فِى الاٌّرْضِ مَرَحًا إِنَّكَ لَن تَخْرِقَ الاٌّرْضَ وَلَن تَبْلُغَ الْجِبَالَ طُولاً
And walk not on the earth with conceit and arrogance. Verily, you can neither rend nor penetrate the earth, nor can you attain a stature like the mountains in height. (17;37)
There is another way of explaining this Ayah;
Ali bin Abi Talhah reported that Ibn Abbas said that,
وَإِن كَانَ مَكْرُهُمْ لِتَزُولَ مِنْهُ الْجِبَالُ
(though their plot was not such as to remove the mountains from their places),
refers to their Shirk, for Allah said in another Ayah,
تَكَادُ السَّمَـوَتُ يَتَفَطَّرْنَ مِنْهُ
Whereby the heavens are almost torn. (19;90)
Ad-Dahhak and Qatadah said similarly