Or HaChaim on Exodus 1:22/אור החיים על שמות א׳:כ״ב

1 ויצו פרעה לכל עמו, Pharaoh commanded his entire nation, etc. Whereas originally Pharaoh's command to the midwives to kill new born boy babies was a secret deal between him and the midwives, something the Hebrew women did not know about, now, in view of the failure of that plan, he resorted to a public announcement; he believed that in view of the continued expansion of the Israelite population he would have popular support for such a draconian measure. An additional factor forcing Pharaoh's hand to go public with the decree to drown all boy babies may have been that according to astrologers Pharaoh foresaw that the redeemer of the Israelites would be born and would end his career prematurely due to water (Sanhedrin 101). Pharaoh mobilised every Egyptian to participate in this decree in order to precipitate this event.

2The Torah says לאמור, i.e. not every Egyptian should personally commit such a murder but that he should tell the Hebrew parent to drown his child seeing it was a Royal decree. Pharaoh's interpretation of what the astrologers had told him was that Moses would find a premature death by water at the hand of an Israelite. This is why he insisted that the Israelites themselves kill the children. The fact that Yocheved herself exposed Moses to a watery death is proof that the Egyptians themselves did not drown the children.

3It is also possible that the meaning of the word לאמור at this point is that only the neighbours of the Israelites were to be involved in this, not the entire population.

4Some of our rabbis felt (Sotah 12) that Pharaoh commanded that all boy babies (Egyptian as well as Jewish) born on a certain day should be drowned as he believed that this was the day on which the Jewish redeemer was to be born. Such an exegesis is homiletics. The plain meaning is that the decree concerned only Jewish boy babies. Had it been in effect for only a single day, why did Yocheved feel she had to hide Moses for three months? Surely the decree was in effect for an indefinite period during the time Moses was born. The words לכל עמו simply mean that "his entire people be acquainted with this decree."