Mukhtasar Sahih Bukhari — Hadith 2172

Narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The three most evil persons in the sight of Allah Almighty are: (1) the one who commits injustice in the Haram of Makkah, (2) the one who, being a Muslim, wishes to follow the customs of ignorance, (3) the one who seeks to shed someone's blood unjustly."