Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 21: The Anger and Appeasal of Viśvāmitra
Text 1.21.3

यदीदं ते क्षमं राजन्गमिष्यामि यथागतम्।
मिथ्याप्रतिज्ञः काकुत्स्थ सुखी भव सबान्धवः॥

yadīdaṁ te kṣamaṁ rājan gamiṣyāmi yathā-gatam
mithyā-pratijñaḥ
kākutstha sukhī bhava sabāndhavaḥ

yadi idam te kṣamam = if this is all you can do; rājan = O king; gamiṣyāmi = I will go away; yathā-āgatam = the way I came; mithyā-pratijñaḥ = you are a man of false promises; kākutstha = O descendant of Kakutstha; sukhī = happy; bhava = be; sa-bāndhavaḥ = with your relatives.

O king, if this is all you can do, I will go away the way I came. O descendant of Kakutstha, you are a man of false promises. Be happy with your relatives!

If all Daśaratha could do was to break promises, Viśvāmitra just wanted to go back. His remark, “Be happy,” is sarcastic.