Shloka 2.18.21
अष्टादशः सर्गः — Kaikeyī Discloses the Boons: Exile to Daṇḍaka and Bharata’s Consecration
प्रियं त्वामप्रियं वक्तुं वाणी नास्योपवर्तते।तदवश्यं त्वया कार्यं यदनेनाश्रुतं मम।।।।
priyaṃ tvām apriyaṃ vaktuṃ vāṇī nāsyopavartate | tad avaśyaṃ tvayā kāryaṃ yad anenāśrutaṃ mama ||
Because you are dear to him, his speech will not let him tell you what is unpleasant. Therefore you must surely do what he once promised to me.
The goddess of speech does not permit him to say an unpleasant thing to you for you are his beloved son. So you must fulfil the promise he has made to me.
Satya (truthfulness) and pratijñā-pālana (keeping promises) are invoked: Kaikeyī claims a prior promise must be fulfilled, framing dharma as obligation to pledged word.
Kaikeyī argues that Daśaratha cannot speak the harsh request himself, so she presses Rāma to comply with the king’s earlier assurance to her.
Rāma’s reliability to uphold vows and the royal word; the verse also highlights how moral language can be used persuasively to compel compliance.