In plain words
One can win victory in any war, however terrible. One can conquer any rākṣasas, however mighty. After they had gone some distance, Lakṣmaṇa put a question. “Swami! Why this teaching of a mantra to me?” To this Viśvāmitra: “My son! You are tender sons; hunger is the fire of the belly. Hunger must not come. While you are eating, who knows from where Tāṭakī will come; while you are sleeping, who knows from where these rākṣasas will come; so you must keep your gaze on the rākṣasas alone. By chanting these two mantras, ‘Bala’ and ‘Atibala’, sleep and hunger will both go, and you will be able to guard the yāga without hindrance,” he taught them. Great souls teach mantras for the sake of peace. So one must not ask foolish questions like, “Knowing that Rāma was an Avatāra, why did he teach Him a mantra?” He did not teach the mantra here thinking of them as mere men, or as God. It was only so as to act as the time and the occasion required. Students! Tomorrow I will surely teach the principle of Viṣṇu. It will be easier still. The oneness of these three, Ātma, mind and speech, is the essence of the Upaniṣads. Tomorrow we shall learn about this.