1. This appeal arises out of a suit brought by the plaintiffs-respondents for a declaration that the property in suit was not liable to sale in execution of two decrees. The facts appear to be as follows. One Badri Prasad had two simple money-decrees against Lal Singh, the father of the plaintiff, and two other persons. He put those decrees in execution, had the property in dispute sold at auction on the 22nd of April 1919 and purchased it himself. Before this sale, however. Mohar Singh, the present plaintiff, and one of the sons of be judgment-debtor had brought a suit for a declaration that the property in dispute was joint family property and as such was not liable to sale in execution of those decrees. In that suit the plaintiff's allegation was that the debts were not taken for family necessity but were taken by other persons for whom the plaintiff's father stood surety. In that suit the question of the non liability of the son to pay the amount of the decrees on the ground of the father's immorality, or that the debts were of a nature for which the son was not liable under the Hindu Law was not raised. That suit was dismissed. The decree was allowed to become final and after wards the present suit was brought to avoid the sale on the ground that the debts were tainted with immorality. The first Court came to the conclusion that the present suit was barred by the rule of res judicata. It might be mentioned here that the plaintiff is a minor, and the present suit was brought through a next friend other than the one through whom the first suit had been filed. The learned Judge of the lower Appellate Court has come to the conclusion, following a ruling of the Madras High Court in preference to a ruling of this Court, that the present suit is not barred by the rule of res judicata and has decreed the claim for setting aside the sale. He has not come to any finding on the question whether the debts were tainted with immorality or not. We think it necessary to invite the lower Court's attention to the recognised principle that it is bound to follow the ruling of this Court in preference to the ruling of other High Courts where the two Courts differ. We think that the Judge of the Court below was distinctly in error in trying to follow a rule of law laid down by the Madras High Court saying that, where there are mixed questions of law and fact, the rule of res judicata would operate but it would not so operate if there is a wrong decision on a pure question of law. The cases cited by the Court below were mostly cases for enforcement of recurring liability such as either suits for rent or suits for maintenance. To those classes of suits different considerations apply. The present suit is clearly barred by the rule of res judicata. The present ground of attack, namely, that the debts were tainted with immorality, ought to have been made a ground of attack in the previous suit if the plaintiff wanted to avoid the sale of family property. In our opinion, it is not open to the plaintiff now to avoid the sale on that ground. In our opinion, this appeal must be allowed. We accordingly allow the appeal, set aside the decree of the learned Subordinate Judge and restore that of the Court of first instance with costs in all Courts.