The Midrash relates that when the Egyptians were warned that their first-borns would die in the 10th plague, they replied (in barbaric fashion), “We each have 10 sons! We’ll have to sacrifice our first-born for the cause but under no circumstances will we free our Jewish slaves!”
To their chagrin, when the plague struck, many of their children were lost. They investigated and discovered that Hashem was revealing the fruits of their promiscuous ways. How so? Many Egyptian men lived with one woman. Each of her sons was a firstborn from his father. Conversely if one man lived with ten different women, each woman’s first born was the first from their mother!
Regarding the Jews, however, the Midrash states that the Egyptians used to boast to each other about the many Jewish women they subjugated. Hashem then bore testimony to refute their claims and to prove that the Jewish slavewomen did not succumb to their masters. How and when did Hashem bear witness to this? By the plague of the death of the firstborn, Hashem skipped over the house of the Jews and they were all spared! If it was indeed true that the Jewish women were violated, Then some Jews would have died as well, being that they were firstborn form an Egyptian father!
Evidently, although the Jews were enslaved in Egypt for 210 years, they did not assimilate and maintained their high moral standards despite being exposed to this most debased society!
Another lesson emerges as well. It states in Pirkei Avos-Ethics of our Fathers, that one who transgresses and commits a sin in private (thinking that no one sees him), receives retribution in public, displaying that Hashem observes and records all our deeds. This is what occurred in Egypt when so many firstborns were struck down in the plague. How much more so, when someone performs a Mitzvah-a good deed, will he receive his just reward.
By Rabbi Sharaga Thav