Said in verse 46 was:

وَقَدْ مَكَرُ‌وا مَكْرَ‌هُمْ وَعِندَ اللَّـهِ مَكْرُ‌هُمْ وَإِن كَانَ مَكْرُ‌هُمْ لِتَزُولَ مِنْهُ الْجِبَالُ

And they worked out their plot and whatever they plot is be-fore Allah, even though their plot is such as would move the mountains.

Which can be explained further by saying that those people tried to demolish the true faith and put in action their deadliest plans to bring harm to Muslims who had embraced the call of truth. But, all plans made by them, open or concealed, lie exposed before Allah Ta’ ala who is fully aware of them, and comprehensively capable of foiling them - even though, their plots were so precise and lethal that they would have made mountains back out from their place, but finally, nothing worked before the perfect power of Allah Ta’ ala.

The hostile plots and plans mentioned here may possibly mean the plots and plans made by people destroyed in the past, for example, Nimrud, Pharaoh, the people of ` Ad and Thamud and others. And it is also possible that the text is referring to the Mushriks of Arabia who hatched many deep-seated and far-reaching conspiracies against the Holy ﷺ ، but they were all foiled by Allah Ta` ala.

There are a good many commentators who have taken the word: (in) appearing in وَإِن كَانَ مَكْرُ‌هُمْ (even though their plot) as a particle of negation and explain the verse to mean that 'though they made many plots but it was not possible for their plots to make mountains move away from their place - and the mountain here means the high determination of the Holy Prophet ﷺ which remained totally unaffected by any of the moves made by the disbelievers.