Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 64: Viśvāmitra Falls Prey to Anger
Text 1.64.7

त्वं हि रूपं बहुगुणं कृत्वा परमभास्वरम्।
तमृषिं कौशिकं रम्भे भेदयस्व तपस्विनम्॥

tvaṁ hi rūpaṁ bahu-guṇaṁ kṛtvā parama-bhāsvaram
tam
ṛṣiṁ kauśikaṁ rambhe bhedayasva tapasvinam

tvam hi rūpam bahu-guṇam kṛtvā parama-bhāsvaram = embellish your most resplendent beauty and; tam ṛṣim kauśikam = of the sage Kauśika; rambhe = Rambhā; bhedayasva = agitate mind of; tapasvinam = the ascetic.

Rambhā, embellish your most resplendent beauty and agitate the mind of the ascetic sage Kauśika.

“Embellish your beauty” indicates that Rambhā should engage herself in amorous activities.