Jamieson, Fausset and Brown on Leviticus 24:10

10. the son of an Israelitish woman, &c.--This passage narrates the enactment of a new law, with a detail of the circumstances which gave rise to it. The "mixed multitude" [Ex 12:38] that accompanied the Israelites in their exodus from Egypt creates a presumption that marriage connections of the kind described were not infrequent. And it was most natural, in the relative circumstances of the two people, that the father should be an Egyptian and the mother an Israelite.