अप्रार्थितोपि वृद्धस्तु वटुना वारितोपि च |
दास्यामि कन्यामिन्येव प्रतिजज्ञे पुरो हरेः ||
Brahmachari did not request him to do so. In fact he cautioned the old man not to make a promise to that effect. But the old man insisted on that promise in the presence of Lord Shri Krishna.