Shriram was grief stricken when Sita was abducted by Ravan. Seeing this Parvati said to Shankar, “Look, how Shriram pines for His wife, the God whose name We chant day and night ! Many times even ordinary people do not lament so much.”
Hearing this Shankar said, “Parvati, you are mistaken; this grief of Shriram is outwardly. Since God has incarnated as a human being, He is behaving accordingly.” Parvati said, “I do not believe you; because Shriram is embracing trees while calling out Sita, Sita. He has really lost His bearing.” Hearing Her commentShankar said, “Let us try something. You transform yourself as Sita and appear before Him. Let us see what happens.” As planned, Parvati transformed Herself as Sita and stood in Shriram's way; but Shriram did not pay any attention to her.
Many times she tried to face Shriramchandra; but He did not even look at her.
Seeing His attitude, Parvati said to him, “What is this ! When Sita is before you, you spurn her!” That time Shriram smiled gently and said, “Jaganmata (Mother of the world) You are Adi-Maya (Primal energy). I have recognised you. Please leave.”
Hearing these words, Parvati was embarrassed and said, “Ramachandra, I had come to test you with Shankar’s permission. Now I have realised that you are Vishnu incarnate .”
Sri Gondavalekar Maharaj’s biography and literature, page 695
Reference : Shivpuran, P.N. Joshi