Tafsir of Al-Kahf 18:85

(Then he followed) — with the [hamza] al-qat’ (the hamza of severance). The fa is fasiha (an eloquent connective particle), and the implied meaning is: "He wished to reach the west, so he followed a path."

(A path) — that would lead him to it. It is possible that the intention of reaching the west first was because it was closer to him. It has been said: [He followed it] to observe the solar movement, and this is not because the western direction is superior to the eastern direction, as some Westerners have claimed. For, as Jalal al-Din al-Suyuti said, there is no definitive proof for the superiority of one of the two directions over the other due to the conflict of evidence.

Nafi’ and Ibn Kathir read it as fattaba’a (فَاتَّبَعَ) with hamzat al-wasl (the connective hamza) and a tashdid (doubling) on the ta, and likewise in what follows. Some have suggested that both [readings] mean the same thing and both take a single object. It has also been said that atba’a (أَتْبَعَ) with the qat’ takes two objects, and the implied meaning here is "he followed a path with another path," or "he followed his affair with a path," like the saying of the Almighty: "And We pursued them in this world with a curse."

Abu Ubayd said: Ittaba’a (اتَّبَعَ) with the wasl is used for [traveling] on a journey, while atba’a (أَتْبَعَ) with the qat’ means to overtake, like the saying of the Almighty: "But a piercing flame followed him (فَأَتْبَعَهُ)." Yunus said: Atba’a (أَتْبَعَ) with the qat’ is for one who is earnest, hastening, and insistent in pursuit, whereas ittaba’a (اتَّبَعَ) with the wasl merely entails moving and following.