Exodus 2:1-3

1Now a man of the house of Levi [the priestly tribe] went and took as his wife a daughter of Levi.

2The woman conceived and gave birth to a son; and when she saw that he was [especially] beautiful and healthy, she hid him for three months [to protect him from the Egyptians].

3When she could no longer hide him, she got him a basket (chest) made of papyrus reeds and covered it with tar and pitch [making it waterproof]. Then she put the child in it and set it among the reeds by the bank of the Nile.