Section 10 of the Code of Civil Procedure, 1908, deals with the principle of res sub judice (meaning 'a matter under judgment'). It provides that no Court shall proceed with the trial of any suit in which the matter in issue is also directly and substantially in issue in a previously instituted suit between the same parties. The language of the section uses the word "shall," indicating that the provision is mandatory. Once the conditions of Section 10 are met, the court has no discretion; it must stay the trial of the subsequent suit. The objective is to prevent courts of concurrent jurisdiction from simultaneously trying parallel suits on the same cause of action.