When she had opened it. — The princess opened the ark herself, perhaps suspecting what was inside, perhaps out of mere curiosity.
The babe (rather, the boy) wept. Through hunger, or cold, or perhaps general discomfort. An ark of bulrushes could not have been a very pleasant cradle.
She had compassion on him. — The babe’s tears moved her to pity; and her pity prompted her to save it. She must have shown some sign of her intention — perhaps by taking the child from the ark and fondling it — before Miriam could have ventured to make her suggestion. (See the next verse.)
This is one of the Hebrews’ children. — The circumstances spoke for themselves. No mother would have exposed such a “goodly child” (Exodus 2:2) to so sad a death but one with whom it was a necessity.