The parties having by the reference chosen their own judges, and agreed to abide by their report, we are not at liberty to consider any question but that which is distinctly presented to us by the referees : and that is, whether an agreement on the part of the plaintiff to conceal the fact of his having purchased, is per se fraudulent, and so *109avoids the sale to him. And we are of opinion that it is mere matter of evidence, strong perhaps against the plaintiff, but still only evidence, capable of explanation, and therefore, according to the agreement of the parties, judgment must be for the plaintiff on the report.2