ॐ Why did bhagavan Rama ask Sita ma to perform an agniparīkṣa?
After the victory of Rama bhagavan in the battlefield against Ravaṇa, Sita ma is released and set to return to Śrī Rama. However, a rumour on Sita ma started. There was a doubt cast on Sita ma about how pure and loyal she is because she stayed in Laṅka where Ravaṇa kept her as captive.
The couple had stayed apart from the moment Ravaṇa had abducted Sita ma after she crossed the lakṣmaṇa rekha guarding their hut in the forest of Pañcavaṭī until Śrī Rama killed Ravaṇain the battlefield and secured her release. All this time she had stayed into Ravaṇa's captivity.
Rama bhagavan could have said “I trust my wife” and that/those person(s) who raised the doubt to mind his/their own business. However, bhagavan said that Sita ma should undergo an agniparīkṣa. Why?
1. In any ancient kingdom, the king is considered as the highest in the kṣatriya hierarchy. The king's the representative of Īśvara in the mortal kingdom. In that capacity, it is the king’s responsibility to sustain the laws of Īśvara (physical, biological, social, psychological and so on). And, the moment one has freewill which all human beings possess, one needs an order and somebody to govern. One needs somebody to look upon the whole kingdom. It is the king's responsibility to govern and sustain these laws of Īśvara. The king is responsible for the well-being of the praja, his subjects. He has a duty towards them.
Similarly, Śrī Rama had the responsibility of his praja, of his kingdom. So when somebody raises a doubt on Sita ma which will look bad on Sita ma, on Rama bhagavan and the whole kingdom, he has the responsibility and duty to address the matter. The king's primary duty is toward his kingdom. All subjects are his children. So, he has to satisfy their concerns.
2. Knowing the tapas that Sita ma has given as a wife by giving up royal comfort and standing by her husband throughout the exile and its ups and downs, Śrī Rama knew his wife would pass such a test. And, as a king, if his praja had a concern, he has to pay heed. This time, the concern was about his wife, a wife like Sita who is a great example of pativratam. So, he had to establish Sita ma as faithful. That’s why he said to do an agniparīkṣa.
3. Now had he refused to take any action or measure or to put to rest the concerns about the matter, this refusal may never have redeemed Sita ma and people may still have doubted her. Therefore it was in hers, his and the kingdom's best interest to set the record clear.
Sita ma passes the test and the couple proceeds to Ayodhya where the rajya abhiṣeka, that is, royal coronation of Śrī Rama takes place. The couple lives a prosperous life ahead. On this note ends Ramayana which is written by ṛṣi Valmīki.
I have a doubt. After tested her and after getting purity certificate from Agni Deva why lord Rama has sent her to forest on a common man's words. At most he could have tested her again before his praja. Pl. Clarify.