Valmiki Ramayana 5.16.15

इयम् सा धर्म शीलस्य जनकस्य महात्मनः ।सुता मैथिलराजस्य सीता भर्तृदृढ व्रता॥

iyam sā dharma śīlasya janakasya mahātmanaḥ |sutā maithilarājasya sītā bhartṛdṛḍha vratā ||

Our plain-language meaning of this verse is waiting for scholar review.