Canto 3 -
Araṇya-kāṇḍa
Chapter 37: Mārīca Advises Rāvaṇa
Text 3.37.20
न सा धर्षयितुं शक्या मैथिल्योजस्विनः प्रिया।
दीप्तस्येव हुताशस्य शिखा सीता सुमध्यमा॥
na sā dharṣayituṁ śakyā maithily ojasvinaḥ priyā
dīptasyeva hutāśasya śikhā sītā sumadhyamā
na = not; sā = the; dharṣayitum = to overpower; śakyā = it is possible; maithilī = Princess of Mithilā; ojasvinaḥ = of one [so] powerful; priyā = the beloved; dīptasya = of a blazing; iva = is like; hutāśasya = fire; śikhā = the flame; sītā = Sītā; sumadhyamā = slender-waisted.
It is not possible to overpower the Princess of Mithilā, the beloved of one [so] powerful. Slender-waisted Sītā is like the flame of a blazing fire.1
1 The flame of a blazing fire may look very beautiful, but it is very dangerous to touch it.