The law on this subject has been fully settled in the modern cases, by an accurate discrimination between the competency and the credibility of witnesses. The stream of justice should, however, be preserved clear and uncontaminated and although a creditor is not excluded frogiving testimony, as such; yet if he acknowledges an expedition, that he shall be bettered by the fate of the cause, (as in the case of M'Veaugh v. Goods, which was properly ruled) he is sensible of a positive interest, that must give a biass to his mind. From the answers of the witness, therefore, we must reject his testimony.