The Mekhilta makes a striking claim about the moral character of the Israelites in Egypt: they were not guilty of sexual immorality. The proof comes from an unexpected source — a verse that describes the one exception to this rule.
(Leviticus 24:10) mentions "the son of an Israelite woman, the son of an Egyptian man." The rabbis noted that Scripture singles out this case precisely because it was unique. The fact that the Torah bothers to identify this particular mixed parentage tells us that such a situation was extraordinary. If intermingling had been common, why would one case merit special mention?
The Mekhilta reinforces this with a poetic reading from the Song of Songs. (Song of Songs 4:12) describes the beloved as "a locked garden, my sister, my bride, a fountain locked." The rabbis interpreted "a locked garden" as referring to the Israelite women — they kept themselves sexually separate from the Egyptians. "A fountain locked" refers to the Israelite men — they too maintained their boundaries.
This teaching served an important theological purpose. The Israelites had lived in Egypt for generations under brutal conditions of slavery. One might assume that centuries of oppression would have eroded their moral standards and communal identity. The Mekhilta insists otherwise. Even under the harshest circumstances imaginable, Israel preserved its distinctiveness. Their sexual fidelity was not merely a personal virtue but a collective achievement — one that the Torah itself commemorates by highlighting the rarity of its violation.