What is if the witness is interested in the case in which he is called to testify?
Can it be a reason to consider his testament much weaker (or even ignore it)? As I know, in the Torah is mainly the number of the witnesses are prescribed. What is the case with their interests, affecting their beliavibility?
Rambam in Mishneh Torah Hilchos Eidus 9 (1) gives
ten categories of disqualifications. Any person belonging to one of them is not acceptable as a witness.
The tenth one is
people who have a vested interest in the matter
So we see that someone with a vested interest in the outcome of the case is disqualified as a witness.
