Which was revealed in Makkah

Surah Hud made the Prophet's Hair turn Gray

Abu `Isa At-Tirmidhi recorded from Ibn `Abbas that Abu Bakr said, "O Messenger of Allah, verily your hair has turned gray." The Prophet replied,

From the second verse begins the delineation of one of the most important and foremost themes, that of Tauhid, the Oneness of Allah Ta` ala. It is said: أَلَّا تَعْبُدُوا إِلَّا اللَّـهَ (that you worship none but Allah). It means that among things stated in these verses the most important and foremost is that no one else should be worshipped except the One Allah.

After that, it was said: إِنَّنِي لَكُم مِّنْهُ نَذِيرٌ‌ وَبَشِيرٌ‌ (Surely, I am for you a warner from Him, and a bearer of glad tidings). It means that the noble messenger of Allah, ﷺ has been commanded to tell the whole world through these verses that he was for them a carrier of warning (against disobedience) and a bearer of glad tidings (of blessings in this life and in the life to come) from Allah.