Sahih Bukhari
Sahih Bukhari Volume 009, Book 083, Hadith Number 003.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 83. Blood Money (Ad-Diyat)
Narrated By 'Abdullah bin 'Umar : One of the evil deeds with bad consequence from which there is no escape for the one who is involved in it is to kill someone unlawfully.