In Exodus 2:5-8, a daughter of Pharaoh is out bathing herself in the river with her maidens. She notices the basket in the reeds and tells one of her slaves to go and get it for her. Pharaoh’s daughter opens the basket to reveal the crying Hebrew child. She is stricken with compassion for the boy and decides to keep him for herself rather than turn him over to be executed by the authorities. This actually teaches us a good moral lesson: insubordination is okay if the command is based upon unjust racist execution. Granted, that’s the kind of lesson a three-year-old figures out for themselves, but this is the bible, we have to take what we can get.
Once she’s sure her brother is in good hands, the Hebrew sister pops out of the reeds and says she can fetch a nurse for the child. Pharaoh’s daughter doesn’t find this amazing coincidence in the least bit suspicious and tells her to go, so the girl leaves to bring her mother. It sounds to me like the sister is trying to make it seem like she’s fetching a random Hebrew wet nurse, not the boy’s biological mother, possibly so Pharaoh’s daughter will never know they’re related. However, the writing is imprecise, so it’s hard to be sure.
This scene differs quite a bit from the 1956 movie. First of all, Pharaoh’s daughter actually get’s a name, Bithiah. And in the movie it is Bithiah who finds the basket and makes her handmaidens as to keep the child a secret. Only she and her slave, Memnet (who is never mentioned in the bible) ever know about the boy being Hebrew. This creates a wonderful plot device, which the movie exploits later on, making it much more interesting than the bible. The movie also gives her a stronger motive for keeping the child than compassion alone, saying that she is unable to conceive, and she believes the child is an answer to her prayers to the Egyptian gods. Finally, in the bible, the sister leads the mother to Pharaoh’s daughter, but in the movie, Memnet is led to the mother (this is mentioned later in the film).