BY THIS SACRED CITY!
VERSES NO.1-7 
Quran starts with oaths when it is going to mention critical and essential realities to incite man's power of thinking and intellect.
For stating that man is always in distress and struggle during his lifetime in the world, it is sworn by the city of Mecca, wherein the Prophet (SA) resided, as well as the founders of Mecca and Kaaba, Abraham and Ismael, to whom even Arabs at the time of Ignorance rendered a remarkable respect.
Considering the life of Prophets and saints of God shows that their life too has been accompanied with various adversities, afflictions and pains, while they were elites of creation. Then, we shall not expect to be excluded from this condition. The reason is that man has no power by himself, but when he has power, he commits sin, and it seems that he finds himself secure from everything. 
There is a group of people who call charity as the waste of wealth, but they had not spent anything for God, but for affectation, pretension and personal purposes.
However, God is omnipresent and encompasses and sees all. He is aware of depth of man's heart and spirit and knows everything.