"Kema'aseh Eretz Mitrayim asher yishavtem bo lo tha'asu..." The prohibition against adopting the "ma'aseh", the practices of the Egyptians (Acharei Mos, 18:3) refers according to many commentaries to the nature of their social interaction that we are supposed to study, learn to deplore, and distance ourselves from. Rabbi Samson Raphael Hirsch explains that the word, "ma'aseh" in Torah indicates social conduct and ultimately "the attitude of a people towards justice and civic life". (see also Meor Vashemesh, Rav Nison Alpert) It is certainly reasonable that slave masters could start out as individuals whose entire world consisted of themselves and their needs. Perhaps that is why we are reminded in that pasuk that we must not emulate the Egyptians "amongst whom we lived". Apparently it is precisely because we have felt the awful sting of a society built on self focus that we should seek with great conviction to protect ourselves from the behaviors that could have contributed to the development of that culture.
The belief that our suffering at the hands of the Egyptians in fact began with behavioral and character flaws would help us understand a phrase that we have repeated many a time in the past few days. Our departure from Mitzrayim is described in Tehillim as "Beis Ya'akov Me'am lo'ez" - "The house of Ya'akov [leaving] a people of strange language". Why did Dovid Hamelech choose to describe our oppressors in such a non-descriptive term, a characteristic that could describe almost any nation? Certainly he could have found some expression that would more surely convey the flavor of the host power throughout our years in exile.
This question led the author of the Torah Temima, Rabbi Baruch Epstien, in his commentary to the sidur, Baruch Sheomar, to translate "me'am loez " in a novel way. He suggests that the Egyptians are referred to as an evil-tongued nation, not a foreign-tongued nation; as perpetrators of La'az - Loshan Horah, not as simply speakers of another tongue. Dovid Hamelech is identifying a tool used by the Egyptian leadership against us; one with which we have become all too familiar throughout our years of wandering. One need only review the opening parshiyos of Shemos, where Pharoh accuses us of harboring unfaithfulness to the very land to whom we had brought the economic stability and prosperity that they were then enjoying. According to the Ramban the Mitzriyim were in fact grateful to Yosef's family and had no ill feelings for them. Pharoh had to wear down those good feelings and convince his people that we were different; different enough to be disinterested in the survival of Egypt. Once the seeds of disenfranchisement were sown, one could easily ask for a tax from those foreigners who were using native resources. A few well placed words could feed into a society so wrapped up with itself that it was unable to integrate others and their needs, ultimately transforming them into treacherous taskmasters.
That is why Dovid Hamelech refers to the House of Ya'akov being extricated from the evil tongued Egyptian society. He comes to remind us that what may seem as a behavioral and moral flaw can eat away at the moral infrastructure of an entire people leaving them bereft of any compassion and standards by which to measure themselves. We are reminded through this Hallel passage that the House of Ya'akov, the Jewish home was redeemed from a surrounding that looked upon it with disapproval and distaste. Having lived through the results of that attitude, we are charged through this prohibition against adopting "ma'aseh Eretz Mitzrayim" and rather we are to use our insulated quarters to instill concern for others, a positive outlook and a focus far beyond oneself.