711. hadíth
وَ رَوَى فَضَالَةُ عَنْ أَبَانٍ قَالَ: سُئِلَ أَبُو عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ عَنْ شَرِيكَيْنِ شَهِدَ أَحَدُهُمَا لِصَاحِبِهِ قَالَ "تَجُوزُ شَهَادَتُهُ إِلاَّ فِي شَيْءٍ لَهُ فِيهِ نَصِيبٌ ".
And Fadalah narrated from Aban, who said: Abu Abdullah (a.s), was asked about two partners, one of whom testified for the other. Imam (a.s) said: "His testimony is valid except in something where he has a share."