Who Is Asiyah, Pharaoh’s Wife?
Question

I am finding it difficult to find some information on Pharaoh's wife;  Asiyah. Can you give me some information on her? Was her submission to Allah kept secret from Pharaoh?
Praise be to Allah.We do not have a lot of information about the righteous woman Asiyah bint Muzahim, the wife of Pharaoh . All the details that have been narrated about her are from the Israiliyyat (stories from Jewish sources), and are not proven in any authentic text as far as we know. 
But it seems – and Allah knows best – that she was one of those who concealed their faith from Pharaoh , then her secret was found out. There follow some of the things that have been narrated about her, with some commentary: 

Allah says (interpretation of the meaning): 

“And Allah has set forth an example for those who believe: the wife of Fir’awn (Pharaoh), when she said: ‘My Lord! Build for me a home with You in Paradise, and save me from Fir’awn (Pharaoh) and his work, and save me from the people who are Zalimun (polytheists, wrongdoers and disbelievers in Allah)’” [al-Tahrim 66:11]

Abu Musa al-Ash’ari said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “The men who attain perfection are many, but there are no women who have attained perfection apart from Asiyah the wife of Pharaoh and Maryam bint ‘Imran, and the superiority of `Aishah over all other women is like the superiority of tharid over all other foods.” (Narrated by al-Bukhari, 3230; Muslim, 2431) 
Ibn `Abbas said: the Messenger of Allah (peace and blessings of Allah be upon him) drew four lines on the ground, then he said, “Do you know what this is?” We said, “Allah and His Messenger know best.” The Messenger of Allah (peace and blessings of Allah be upon him) said: “The best of the women of Paradise are Khadijah bint Khuwaylid, Fatimah bint Muhammad, Asiyah bint Muzahim (the wife of Pharaoh), and Maryam bint ‘Imran – may Allah be pleased with them.” (Narrated by Ahmad, 2663. Classed as sahih by al-Albani in Sahih al-Jami’, 1135)

Anas narrated that the Prophet (peace and blessings of Allah be upon him) said: “Sufficient for you among the women of the world are Maryam the daughter of ‘Imran. Khadijah bint Khuwaylid, Fatimah bint Muhammad and Asiyah (the wife of Pharaoh).” (Narrated and classed as sahih by al-Tirmidhi, 3878)

Al-Hafiz ibn Hajar said:

 “Among the virtues of Asiyah, the wife of Pharaoh, is that she chose death over royal privilege and torment in this world over the luxury in which she was living. And her insight concerning Musa (peace be upon him) was correct when she said “A comfort of the eye for me” [al-Qasas 28:9 – interpretation of the meaning].” (Fath al-Bari, 6/448)
 And Allah knows best.