“And We placed within the earth firmly set mountains, lest it should shift with them, and We made therein [mountain] passes [as] roads that they might be guided.” [Al-Quran 21:31]

Mountains stabilize the earth and keep it steady and lend it weight, lest it should shake with the people, i.e., move and tremble so that they would not be able to stand firm on it — because it is covered with water, apart from one-quarter of its surface. Further, mountains form barriers between one land and another, so Allah created gaps(passes) in the mountains so that people may travel from one place to another.

“And the earth – We have spread it and cast therein firmly set mountains and caused to grow therein [something] of every well-balanced thing.” [Al- Quran 15:19]

“Do you not see that Allah sends down rain from the sky, and We produce thereby fruits of varying colors? And in the mountains are tracts, white and red of varying shades and [some] extremely black.” [Al- Quran 35:27]