Saṃvaraṇa–Tapatī Vivāhaḥ (The Marriage of Saṃvaraṇa and Tapatī) — Mahābhārata, Ādi Parva 163
ततो भीम: शनैर्भुक्त्वा तदन्नं पुरुषर्षभ: । वार्युपस्पृश्य संहृष्टस्तस्थी युधि महाबल:
tato bhīmaḥ śanair bhuktvā tad-annaṁ puruṣarṣabhaḥ | vāry-upaspṛśya saṁhṛṣṭas tasthau yudhi mahābalaḥ ||
Then Bhīma, that bull among men, slowly ate that food. Having sipped water in ritual purification, he became greatly delighted and, mighty in strength, stood firm—ready for battle.
वैशम्पायन उवाच
Even in a martial setting, one should act with discipline and propriety: take what is needed without agitation, observe purification (ācamana), and then enter duty with a composed, resolute mind.
Vaiśampāyana narrates that Bhīma finishes eating the provided food slowly, performs ācamana with water, feels invigorated, and then stands ready and firm for the impending fight.