Srimad Bhagavatam Canto 09, Chapter 10, Text 27

SB 9.10.27

na vai veda maha-bhaga
 bhavan kama-vasam gatah
tejo ’nubhavam sitaya
 yena nito dasam imam
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
O greatly fortunate one, you came under the influence of lusty desires, and therefore you could not understand the influence of mother Sita. Now, because of her curse, you have been reduced to this state, having been killed by Lord Ramacandra.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Not only was mother Sita powerful, but any woman who follows in the footsteps of mother Sita can also become similarly powerful. There are many instances of this in the history of Vedic literature. Whenever we find a description of ideal chaste women, mother Sita is among them. Mandodari, the wife of Ravana, was also very chaste. Similarly, Draupadi was one of five exalted chaste women. As a man must follow great personalities like Brahma and Narada, a woman must follow the path of such ideal women as Sita, Mandodari and Draupadi. By staying chaste and faithful to her husband, a woman enriches herself with supernatural power. It is a moral principle that one should not be influenced by lusty desires for another’s wife. Matrvat para-daresu: an intelligent person must look upon another’s wife as being like his mother. This is a moral injunction from Canakya-sloka (10).
 
matrvat para-daresu
 para-dravyesu lostravat
atmavat sarva-bhutesu
 yah pasyati sa panditah
 
“One who considers another’s wife as his mother, another’s possessions as a lump of dirt and treats all other living beings as he would himself, is considered to be learned.” Thus Ravana was condemned not only by Lord Ramacandra but even by his own wife, Mandodari. Because she was a chaste woman, she knew the power of another chaste woman, especially such a wife as mother Sitadevi.
Srimad Bhagavatam Canto 09, Chapter 10, Text 26
Srimad Bhagavatam Canto 09, Chapter 10, Text 28