In the Name of Allah, the Most Gracious, the Most Merciful.
Swearing by the Sanctity of Makkah and Other Things that Man was created in Hardship
Here Allah has sworn by Makkah, the Mother of the Towns, addressing its resident (during the non-sacred months,) free in this city in order to draw his attention to the significance of its sanctity when its people are in the state of sanctity. Khusayf reported from Mujahid;
لاَ أُقْسِمُ بِهَـذَا الْبَلَدِ
(Nay! I swear by this city;) "The word "La" (Nay) refers to the refutation against them (Quraish). I swear by this city." Shabib bin Bishr narrated from `Ikrimah, from Ibn `Abbas that he said,
(Did We not make for him two eyes, and a tongue and two lips, and showed him the two ways?...90:8-10)
The word najdain is the dual form of najd which means an elevated or conspicuous road. The word najdain signifies the two high and conspicuous ways of good and evil, or of success and destruction. The preceding verse pointed out the ignorance and heedlessness of man. He thinks that Allah has no power over him, and that there is no one watching over his actions. The current verse mentions a few of the organs and abilities that Allah has endowed him with. If he reflects carefully on these endowments, he will appreciate His infinite wisdom and power within himself. He has a pair of eyes. The optic nerves and tissues are rather delicate. They send nervous impulses to the brain when stimulated by light rays from external objects. The structure of the eye itself is most delicate. Each eye consists of a hollow, spherical capsule [ eyeball ], made up of several layers and structures. It is set into a socket in the skull, and is protected by eyelids and eyelashes, and eyebrows. It works like an automatic machine. When a harmful object is seen coming from the front, the eyelids close on their own. The eyelashes block the dust from getting into the eyes. The eyebrows help keep things away from falling into the eyes directly from top. The facial bones, especially the orbit [ eye socket and the cheek bones ], protect the eye, if one were to fall on one's face or something were to fall on the face.
God has commanded man to scale two heights—one is to treat others with justice, and help them in their hour of need. The other is to have firm faith in God. When such belief enters the inner depths of a human being, it does not remain confined to his own thinking but rather makes him become communicative. He then attempts to lead others along the path of Truth which he himself has adopted.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.