Swearing by the Sanctity of Makkah and Other Things that Man was created in Hardship
Allah says,
لَاا أُقْسِمُ بِهَذَا الْبَلَدِ
Nay! I swear by this city;
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;
لَا 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,
لَا أُقْسِمُ بِهَـذَا الْبَلَدِ
Nay! I swear by this city;
"This means Makkah."
Concerning the Ayah;
وَأَنتَ حِلٌّ بِهَذَا الْبَلَدِ