The narrators said: When Allah created the earth and split it open, He sent down an angel from beneath the Throne. The angel descended to the earth until he went beneath the seven earths and placed them upon his shoulder, with one hand in the east and the other in the west, both hands outstretched and holding the seven earths fast. Yet his feet found no firm resting place. So Allah, exalted is He, brought down from Paradise a bull with forty thousand horns and forty thousand legs, and the angel’s feet were set upon its hump. But his feet still did not become steady. Then Allah took a green ruby from the highest level of Paradise, whose thickness was the distance of five hundred years’ travel, and placed it between the bull’s hump and its ear; thereupon the angel’s feet became firm upon it.
The horns of that bull extend beyond the edges of the earth, and its nostrils are in the sea. Each day it takes a breath: when it breathes, the sea rises in tide, and when it draws back its breath, the sea recedes in ebb. Yet the bull’s legs had no firm resting place, so Allah Most High created a rock as thick as seven heavens and seven earths, and the bull’s legs became firm upon it. This is the rock of which Luqman said to his son: “O my dear son, even if it be the weight of a mustard seed, and it be within a rock.” Yet the rock itself had no resting place, so Allah created Nun, the great fish, and placed the rock upon its back. The rest of its body is empty, while the fish is upon the sea, the sea upon the back of the wind, and the wind upon divine power. It is said: The whole world and all that is upon it consists of two letters, by which the Compeller, exalted is He (3), said to it, “Be,” and it was (4).
Ka‘b al-Ahbar said: Iblis made his way to the fish upon whose back the earth rests and whispered to it, saying, “Do you know, O Luwitha, what is upon your back—of nations, animals, trees, and mountains? If you were to shake them, you would cast them off your back.” Luwitha then resolved to do so, but Allah sent a creature which entered its nostril and reached its brain. The fish cried out to Allah for relief from it, and Allah permitted it to leave, so it came out. Ka‘b said: By Him in Whose hand is my soul, the fish watches it and it watches the fish; whenever it contemplates anything of this sort, it returns as it was.
Others said: Nun is the final letter of al-Rahman (the Most Merciful). This is a narration from ‘Ikrimah, from Ibn ‘Abbas.
Al-Hasan, Qatadah, and al-Dahhak said: Nun is the inkwell.