Does Allah Swear by the City of Mecca in the Quran or not?
Brief description of the dubiety
Based on the first verse of Chapter 90 which is Surah al-Balad, some scholars have the opinion that the “la” which starts the verse means that Allah is not swearing by the city of Mecca; however in Chapter 95 which is Surah al-Teen, Allah swears by this city, and thus there appears to be a contradiction in the Quran.
Detailed description of the dubiety
A verse which shows that Allah does not swear by the city of Mecca
In Surah al-Balad, verse 1 it quotes Allah as saying: “I (do not (la uqsimu)) swear by this town.” In this verse, by adding the particle “la” to the present tense verb “I swear” it has clearly been mentioned that Allah does not swear by this city, which refers to the holy city of Mecca.
Verse which states that Allah swears by the city of Mecca
In Surah al-Teen, verse 3 it says: “By this secure town.” In this verse, Allah swears by the city of Mecca and this has been explicitly mentioned.
A summarized response
Considering the use of the Arabic language and the style of the Quran, we know that both the “la of negation” and the “additional la” can precede a present tense verb. The “additional particles” (Huroof Zaidah) in the Arabic language are used in order to emphasize what is being said, thus the phrase “la uqsimu” is an emphatical way of saying “I swear.”
A detailed response
The meaning of “la” in “la uqsimu”
As mentioned, in addition to the “la of negation” we have an “additional la” in the Arabic language. This “la” and the other “additional particles” are used in order to emphasize what is being said, but they do not change the meaning. This usage has a history of being used in Arabic speech and poetry. For example, Imru al-Qays was one of the famous poets from the era of ignorance. At the beginning of some of his poetry, he used to use the “additional la.” For example, he would say: “la I swear by your father, O daughter of Amir, the people cannot claim that I am one who flees.”  In this poem, although the particle “la” has come at the beginning, it does not give a new meaning, rather it is only used to strengthen and emphasize it.
In addition to this, the “additional la” has been used in other places in the Quran as well. For example, in Surah Ta Ha, verses 92-93 is says: “He said, ‘O Haroon! What kept you when you saw them going astray, from following me? Did you disobey my command?’” Here it is clear that Prophet Musa is rebuking his brother in the sense of asking what it was that prevented him from following his command, because if something prevented him from following his command, then not following his command would be acceptable and there would not be a need for rebuking, therefore Prophet Musa is asking what it was that prevented him from following his command, thus the “la” in “la tattabina (you following)” is an “additional la” but it does not have the meaning of negation. 
Based on the above, “la uqsimu” is an emphatic way of swearing by something. Other places in the Quran have also used this phrase, which is clearly used as emphasis, and this can be seen based on the meaning of the verses that follow it. In Surah al-Waqiah, verses 75-76 it says: “So I swear (la uqsimu) by the places where the stars set! And indeed it is a great oath, should you know.” Here verse 76 explicitly states that the phrase “la uqsimu” in the previous verse is a great oath, but the meaning would not match at all if it was taken to mean ‘not swearing.’
Based on this, the “la” in Surah al-Balad, verse 1 where Allah says: “I (la uqsimu) swear by this town,” is using an “additional la” for emphasis, and thus it does not contradict Surah al-Teen, verse 3, rather both of them mention Allah swearing by the city of Mecca.  
- Tafseer Nemunah, Volume 25, Page 274
- Mughni al-Adib, Page 254
- Mughni al-Adib, Pages 254-256