“And He has cast into the earth firmly set mountains, lest it shift with you, and rivers and roads, so that you may be guided; and landmarks. And by the stars they are guided.” (15–16)

“And He has cast into the earth firmly set mountains, lest it shift with you,” that is, lest it move with you (1)—that is, lest it shake and sway.

Mayd is shaking and tilting. Hence the dizziness that afflicts one travelling by sea is called mayad.

Wahb said: When Allah created the earth, it began to sway, and the angels said, “This will not keep anyone settled upon its surface.” By morning, it had been anchored with mountains, yet the angels did not know from what the mountains had been created.

“And rivers and roads,” meaning that He placed within it rivers and different routes, “so that you may be guided” to what you seek and not lose your way. “And landmarks,” meaning markers along the roads. Some said that the statement ends here, after which a new statement begins: “And by the stars they are guided.”

Muhammad ibn Ka‘b and al-Kalbi said: By “landmarks,” He meant the mountains. Thus, mountains serve as landmarks by day, while the stars are landmarks by night.

Mujahid said: He meant stars by both expressions: some of them serve as landmarks, while others are used for navigation.

Al-Suddi said: By “the star,” He meant the Pleiades, the stars of the Great Bear, the two Farqads, and the Pole Star, by which people find their way to routes and the direction of prayer.