This story is on the Prophet Muhammad's (salAllahu alayhi wassalaam) Night Journey to Jerusalem (The Isra'):
The Prophet (salAllahu alayhi wassalaam) smelled a very nice odour. He asked Angel Jibril (alayhis salam) about this pleasant scent and Angel Jibril (Alayhis salam) informed him this good smell was coming from the grave of the woman whose duty used to be to comb Pharaoh's daughter's hair.
This woman was a good, pious believer. One day, as she was combing Pharaoh's daughter's hair, the comb fell from her hand.
At this she said, "Bismillah."
The Pharaoh's daughter asked her, "Do you have a God other than my father?
" The woman said, "Yes. My Lord and the Lord of your father is Allah."
Pharaoh's daughter told her father what had happened. Pharaoh demanded this woman blaspheme and leave Islam, and not be a Muslim anymore, but she refused. At that, Pharaoh threatened to kill her children.
He brought a great pot of water and built a great fire under it. When the water boiled, Pharaoh brought her children and started to drop them into that pot one after the other.
Throughout all this, the woman remained steadfast to Islam - and refused to leave Islam, even when Pharaoh reached her youngest child -- a little boy still breast feeding -- but she felt pity for him.
At that, Allah enabled this child to speak. He said to his mother, "O Mother, be patient. The torture of the Hereafter is far more severe than the torture of this life, and do not be reluctant, because you are right."
At this the woman requested Pharaoh collect her bones and the bones of her children and bury them in the same grave. Pharaoh promised her that -- then dropped her into that boiling water. She died as a martyr.
The good odour the Prophet (salAllahu alayhi wassalam) smelled coming from her grave is an indication of her high status.