Shloka 2.37.21
अयोध्याकाण्डे सर्गः ३७ — चीरधारणं, सीतासंकल्पः, वसिष्ठोपदेशः (Bark-Robe Episode and Vasistha’s Admonition)
चीरे गृहीते तु तया समीक्ष्य नृपतेर्गुरुः।निवार्य सीतां कैकेयीं वसिष्ठो वाक्यमब्रवीत्।।2.37.21।।
cīre gṛhīte tu tayā samīkṣya nṛpater guruḥ | nivārya sītāṁ kaikeyīṁ vasiṣṭho vākyam abravīt || 2.37.21 ||
When he saw that she had taken up the bark garment, Vasistha—the king’s preceptor—restrained Sita and spoke to Kaikeyi these words.
When Sita wore the bark garments, Vasistha, the king's preceptor who was watching this restrained her (Sita) and said to Kaikeyi:
Dharma includes guidance and correction by rightful authority: the royal guru intervenes to regulate what is proper and to question excess or impropriety in Kaikeyi’s demands.
After Sita accepts the bark garment, Vasistha steps in, restrains Sita, and turns to address Kaikeyi.
Guru-dharma (responsible counsel): Vasistha acts as moral guardian of the royal household and its righteous boundaries.