As-Sakina

In His name, most Gracious, most Merciful.

Narrated by Al-Bara'bin Azib:

A mane was reciting Surah al-Kahf and his horse was tired with two ropes beside him. A cloud came down and spread over that man, and it kept on coming closer and closer to him till his horse started jumping (as if afraid of something). When it was morning, the man came to the Prophet, and told him of that experience. The Prophet said, "That was As-Sakina (tranquility) which descended because of (the recitation of) the Qur'an."

[Sahih al-Bukhari 6:61 #531, at-Tirmidhi 2810/A]