Canto 2 -
Ayodhyā-kāṇḍa
Chapter 34: Rāma, Lakṣmaṇa and Sītā Meet Daśaratha
Text 2.34.37
वञ्चना या तु लब्धा मे तां त्वं निस्तर्तुमिच्छसि।
अनया वृत्तसादिन्या कैकेय्याभिप्रचोदितः॥
vañcanā yā tu labdhā me tām tvaṁ nistartum icchasi
anayā vṛtta-sādinyā kaikeyyābhipracoditaḥ
vañcanā yā tu labdhā = she had deceptively obtained; me = from me; tām = a promise done to her that; tvam = You; nistartum = to fulfill; icchasi = want; anayā = by this; vṛtta-sādinyā = who has destroyed the conduct appropriate to my royal dynasty; kaikeyyā = Kaikeyī; abhipracoditaḥ = impelled.
Impelled by this Kaikeyī who has destroyed the conduct appropriate to my royal dynasty, You want to fulfill a promise done to her that she had deceptively obtained from me.
Daśaratha had given a general promise to fulfill any two boons, but Kaikeyī asked for two specific boons—to enthrone Bharata and to exile Rāma. This is how she cheated him.