מדרש על תהילים 2:5

And sent her handmaid to fetch it (Ps. 2:5). Her hand was extended and stretched forth. Then she took the child and brought him to the Egyptian women to be nursed, but he refused their breasts. Surely it is permissible to be nursed by them. We have been taught that an Israelite may not suckle the child of an idolater, but that an idolater may suckle the child of an Israelite if she does so with her permission. What is meant by “with her permission”? It means that if she eats the food of Israelites she may nurse him. The Holy One, blessed be He, declared: In the future, this child will speak with Me, and the Egyptian women will then say: “I nursed the one who now speaks with the Shekhinah.” Therefore, he refused their breasts.