Hadith 6105 - Good Manners and Form (Al-Adab) - Sahih Al-Bukhari - صحيح البخاري - Collection of Actions, Sayings and Teachings of Prophet Muhammad (صلى الله عليه و سلم) - Kutub as-Sittah

78. Good Manners and Form (Al-Adab) - كتاب الأدب

73) Chapter: Whoever calls his brother a Kafir without any grounds

Narrated Thabit bin Ad-Dahhak:

The Prophet (ﷺ) said, "Whoever swears by a religion other than Islam (i.e. if he swears by saying that he is a non-Muslim in case he is telling a lie), then he is as he says if his oath is false and whoever commits suicide with something, will be punished with the same thing in the (Hell) fire, and cursing a believer is like murdering him, and whoever accuses a believer of disbelief, then it is as if he had killed him."

Reference: 6105
English reference: Vol. 8, Book 73, Hadith 126
In-book reference: Book 78, Hadith 132
Grade: Sahih
Read this hadith from Darussalam Collection

73) باب مَنْ كَفَّرَ أَخَاهُ بِغَيْرِ تَأْوِيلٍ فَهْوَ كَمَا قَالَ

حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا وُهَيْبٌ، حَدَّثَنَا أَيُّوبُ، عَنْ أَبِي قِلاَبَةَ، عَنْ ثَابِتِ بْنِ الضَّحَّاكِ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏‏‏.‏ "‏ مَنْ حَلَفَ بِمِلَّةٍ غَيْرِ الإِسْلاَمِ كَاذِبًا فَهْوَ كَمَا قَالَ، وَمَنْ قَتَلَ نَفْسَهُ بِشَىْءٍ عُذِّبَ بِهِ فِي نَارِ جَهَنَّمَ، وَلَعْنُ الْمُؤْمِنِ كَقَتْلِهِ، وَمَنْ رَمَى مُؤْمِنًا بِكُفْرٍ فَهْوَ كَقَتْلِهِ ‏"