Nahj al-Balāgha, no. 1071

He also created its high hills, rocks of stones and lofty mountains. He put them in their positions and made them remain stationary. Their peaks rose into the air while their roots remained in the water. In this way He raised the mountains above the plains and fixed their foundations in the vast expanse wherever they stood. He made their peaks high and made their bodies lofty. He made them like pillars for the earth and fixed them in it like pegs. Consequently, the earth became stationary; otherwise it might bend with its inhabitants or sink inwards with its burden, or shift from its positions.