I heard Messenger of Allah (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. (Using translation from Muslim 2813a)
سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ عَرْشُ إِبْلِيسَ عَلَى الْبَحْرِ ثُمَّ يَبْعَثُ سَرَايَاهُ فَيَفْتِنُونَ النَّاسَ فَأَعْظَمُهُمْ عِنْدَهُ أَعْظَمُهُمْ فِتْنَةً