This Surah was revealed during the same period as that of Surah Ad-Duha, the early period at Makkah.
Allah expanded the breast of the Prophet, relieved his burden and exalted his fame.
This Surah is also to console and encourage the Prophet (pbuh). He never had to encounter the conditions which he suddenly had to encounter after embarking on his mission of inviting people to Islam. This was by itself a great revolution in his life. When he started preaching the message of Islam, the same society which had esteemed him with unique honor, turned hostile to him. The same relatives and friends, the same clansmen and neighbors, who used to treat him with the highest respect, began to shower him with abuse and insult. No one in Makkah was prepared to listen to him; he was being ridiculed and mocked in the street and on the road; and at every step he had to face new difficulties. Although he gradually became accustomed to the hardships, even as they became more severe, yet the initial stage was very discouraging for him. That is why Surah Ad-Duha was sent down first to console him, and then this Surah.
This Surah states that Allah has bestowed three major favors on the Prophet: the first is the blessing of Sharh Sadr (opening up of the breast), the second by removing from him the heavy burden that was weighing down his back before the call, and the third by exalting his renown the like of which has never been granted to any man before.
In conclusion, the Prophet is instructed: "You can develop the power to bear and resist the hardships of the initial stage only by one means, and it is this: `When you are free from your occupations, you should devote yourself to the labor and toil of worship, and turn all your attention exclusively to your Rabb."