Mughira and Ibrahim, may Allah have mercy on them, said: If two among the heirs bear witness (regarding a debt or a bequest upon the deceased), then it will be permissible for all the heirs; and if only one heir bears witness, then the payment (of that debt or bequest) will be from his own share and portion.
Hadith Referenceسنن دارمي / من كتاب الوصايا / 3254
Shu’bi (may Allah have mercy on him) says: If one of the heirs gives testimony, then the payment will be made from his share; in the end, he said: the payment will be made from the shares of all the heirs.
Hadith Referenceسنن دارمي / من كتاب الوصايا / 3255