Hadithcore
Sahih al-Bukhari, 6882
sahih

Narrated Ibn `Abbas:

The Prophet (ﷺ) said, "The most hated persons to Allah are three: (1) A person who deviates from the right conduct, i.e., an evil doer, in the Haram (sanctuaries of Mecca and Medina); (2) a person who seeks that the traditions of the Pre-lslamic Period of Ignorance, should remain in Islam (3) and a person who seeks to shed somebody's blood without any right."

حَدَّثَنَا أَبُو الْيَمَانِ، أَخْبَرَنَا شُعَيْبٌ، عَنْ عَبْدِ اللَّهِ بْنِ أَبِي حُسَيْنٍ، حَدَّثَنَا نَافِعُ بْنُ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ ‏

‏ أَبْغَضُ النَّاسِ إِلَى اللَّهِ ثَلاَثَةٌ مُلْحِدٌ فِي الْحَرَمِ، وَمُبْتَغٍ فِي الإِسْلاَمِ سُنَّةَ الْجَاهِلِيَّةِ، وَمُطَّلِبُ دَمِ امْرِئٍ بِغَيْرِ حَقٍّ لِيُهَرِيقَ دَمَهُ ‏

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References2 variants
In-Book Reference
Book 87, Hadith 21
USC-MSA web (English) reference
Vol. 9, Book 83, Hadith 21 (deprecated numbering scheme)