The preceptor is of benevolent disposition and the Pandavas are trying their utmost (to slay him). United together you will protect him while he will be engaged in destroying his enemies in battle.
आचार्यो हि सुसंयत्तो भृशं यत्ताश्च पाण्डवाः। तं रक्षत सुसंयत्ता निघ्नतं शात्रवान् रणे॥