Shloka 5.1.159
समुद्रलङ्घनारम्भः — Commencement of the Ocean-Crossing
प्रविश्य वदनं मेऽद्य गन्तव्यं वानरोत्तम।वर एष पुरा दत्तो मम धात्रेति सत्वरा।।।।व्यादाय विपुलं वक्त्रं स्थिता सा मारुतेः पुरः।
praviśya vadanaṃ me 'dya gantavyaṃ vānarottama | vara eṣa purā datto mama dhātreti satvarā || vyādāya vipulaṃ vaktraṃ sthitā sā māruteḥ puraḥ |
“O best of the vānaras, today you must go only after entering my mouth; such was the boon once granted to me by Dhātṛ (Brahmā).” Saying so, she quickly opened her vast mouth and stood before the son of the Wind.
"O best vanara! you must pass through my mouth today. Such is the boon granted to me by Brahma in the past". Then she quickly opened her big mouth and stood.
It frames a dharmic trial: divine boons create binding obligations, and the hero must respond with intelligence and truthfulness without abandoning his righteous goal.
Surasā declares the condition of her boon—Hanumān must enter her mouth to pass—then opens her mouth to enforce the test.
Courage under constraint—Hanumān must meet a supernatural requirement while preserving his mission’s integrity.