It is mentioned in the book Raudatus Safa that Pharaoh�s daughter had a maid who was under her command and who used to comb her hair, etc. She had believed in Musa alayhis salam. However, she did not expose her iman out of fear for Pharaoh.
Once while she was combing Pharaoh�s daughter�s hair, the comb fell from her hand. When she bent down to pick it up, she recited Bismillah. The daughter asked her: "What was it you recited just now? Whose name is that?" She replied: "it is the name of the one who created your father and also gave him a kingdom." She became astonished and remarked: "Is there anyone greater than my father!" Saying this she ran out to her father, and related the entire incident him.
Pharaoh became extremely angry, called for the maid, and threatened her.
However she unhesitatingly said: " Do whatever you wish, I will not leave my iman."
Nails were fastened to her hands and feet and thereafter hot ash and embers were placed on her. When this had no effect on her, a child who was in her lap was taken and thrown into the fire. While the child was in the fire, it said: "Mother! Be patient and don�t ever leave your iman." She remained steadfast on her iman until she was also thrown into that fire.
Source: Bahesti Zewar