Jami' at-Tirmidhi
Jami` at-Tirmidhi 2637
حَدَّثَنَا قُتَيْبَةُ، عَنْ مَالِكِ بْنِ أَنَسٍ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " أَيُّمَا رَجُلٍ قَالَ لأَخِيهِ كَافِرٌ فَقَدْ بَاءَ بِهِ أَحَدُهُمَا " . هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ غَرِيبٌ . وَمَعْنَى قَوْلِهِ بَاءَ يَعْنِي أَقَرَّ .
Unreviewed translation. All hadiths in this collection are available in five languages. Titles and introductions may remain in Arabic.
Ibn ‘Umar reported that the Prophet said: ‘If a man says to his brother, “Disbeliever,” the charge returns upon one of the two.’ This hadith is hasan sahih gharīb. The phrase ‘returns upon him’ (bā’a bihi) means ‘acknowledged/incurred it.’
Notes and open questions — unreviewed
The source provides a brief lexical gloss for bā’a bihi; the wording is rendered without specifying which of the two bears the charge.