Sahih Bukhari Volume 1, Book 3, Hadith 110

حَدَّثَنَا مُوسَى، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ أَبِي حَصِينٍ، عَنْ أَبِي صَالِحٍ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏"‏ تَسَمَّوْا بِاسْمِي وَلاَ تَكْتَنُوا بِكُنْيَتِي، وَمَنْ رَآنِي فِي الْمَنَامِ فَقَدْ رَآنِي، فَإِنَّ الشَّيْطَانَ لاَ يَتَمَثَّلُ فِي صُورَتِي، وَمَنْ كَذَبَ عَلَىَّ مُتَعَمِّدًا فَلْيَتَبَوَّأْ مَقْعَدَهُ مِنَ النَّارِ ‏"

Narrated By Abu Huraira : The Prophet said, "Name yourselves with my name (use my name) but do not name yourselves with my Kunya name (i.e. Abu-l Qasim). And whoever sees me in a dream then surely he has seen me for Satan cannot impersonate me. And whoever tells a lie against me (intentionally), then (surely) let him occupy his seat in Hell-fire."