The Rocky Tract - 15:19
We enlarged the earth and placed firm mountains in it and We created therein everything according to a perfect measure.
Why were firm mountains placed on the earth?
The Bee/16:15
And He has placed in the earth stabilizers so that you may not be shaken, and rivers and roads so that you may find the way,
Luqman/31:10
He created the heavens without a pillar that you see. And He placed stabilizers on the earth that you may not be shaken, and He spread therein every kind of creature. And We rained down water from the sky, and We caused to grow therein every beautiful variety.
The Prophets/21:31
We placed mountains on the earth so that it might not shake them, and We made in it wide passages for them to find the way.
Those Who Pull Out/79:32
He has also made the mountains.