It is one of the Makki Surahs, related with the Day of Judgement and doctrine. Allah (swt) has arranged the Holy Qur’an in a special way, we find five consecutive Surahs starting with an oath: Al-Fajr, Al-Balad, Ash-Shams, Al-Lail and Ad-Dhuha. Then comes Surah Ash-Sharh which does not start with an oath, as if to complement this group of Surahs.