Canto 2 -
Ayodhyā-kāṇḍa
Chapter 5: Vasiṣṭha Prepares Rāma for the Coronation
Text 2.5.11
इत्युक्त्वा स तदा राममुपवासं यतव्रतम्।
मन्त्रवत्कारयामास वैदेह्या सहितं मुनिः॥
ity uktvā sa tadā rāmam upavāsaṁ yata-vratam
mantravat kārayām āsa vaidehyā sahitaṁ muniḥ
iti = thus; uktvā = having spoken; saḥ = the; tadā = then; rāmam = Rāma; upavāsam = take up the fasting; yata-vratam = and observance of the vow [required for the coronation]; mantravat = with the required mantras; kārayām āsa = made; vaidehyā = Vaidehī; sahitam = and; muniḥ = sage.
Having spoken thus, the sage then made Rāma and Vaidehī take up the fasting and observance of the vow [required for the coronation] with the required mantras.
1 Technical note: bhavān upavāsam karotu.
NOTE. Prabhupāda remarks on the general principles behind fasting in Vedic culture thus:
One should not fast unnecessarily or against Vedic injunctions. One should not fast for some political purpose; that is described in Bhagavad-gītā as fasting in ignorance, and anything done in ignorance or passion does not lead to spiritual advancement. Everything done in the mode of goodness does advance one, however, and fasting done in terms of the Vedic injunctions enriches one in spiritual knowledge. (Bhagavad-gītā 10.4-5 purport)
Since Rāma appeared to demonstrate the proper behavior of a human being, He fasted in accordance with the injunction of the sage Vasiṣṭha.