وَحَدَّثَنِي مَالِكٌ، أَنَّهُ بَلَغَهُ أَنَّ عُمَرَ بْنَ الْخَطَّابِ، قَالَ لاَ تَجُوزُ شَهَادَةُ خَصْمٍ وَلاَ ظَنِينٍ ‏.‏

Malik related to me that Umar ibn al-Khattab said, "The testimony ofsome one known to bear a grudge or to be unreliable is not accepted." Translation Not Available

Book Ref: Muwatta Imam Malik Book 36 Hadith 1406
Web Ref:  Muwatta Imam Malik Book 36 Hadith 4

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