Sahih Muslim
The Book Giving Description of the Day of Judgement, Paradise and Hell (Kitab Sifat Al-Qiyamah wal Janna wan-Nar)
Book Number: 039 / Hadith Number: 6754
Jabir reported: I heard Allah's Messenger (way peace be upon him) as saying: The throne of Iblis is upon the ocean and he sends detachments (to different parts) inorder to put people to trial and the most important figure in his eyes is one who is most notorious in sowing the seed of dissension.