All the first-born obviously refers to “every first-born son” (Good News Translation). (See 4.23, where “son” is specified.) In the land of Egypt, however, limits the first-born to the Egyptian families. Unless otherwise specified, the Hebrew term refers to the first-born male of a human father. In languages that must specify whether it is the first-born of the father or the mother, it may be necessary to indicate both, since the first-born of the maidservant is also mentioned. One way to avoid this problem is to say “the firstborn son in every family.” Shall die is the general word for dying, without indicating the cause. (In 4.23, however, the verb “to slay” is used.) Contemporary English Version has a good translation model: “the first-born son in every family will die.” However, it will also be helpful to indicate that these are Egyptian families; for example, “and the firstborn son in every Egyptian family will die.”

From the first-born of Pharaoh begins an inclusive statement, starting within the royal family and moving down to the oldest son of the lowest maidservant. Who sits upon his throne is ambiguous. The Hebrew participle may be understood either as “the one sitting” (that is, the king), or as “the one about to sit” (that is, the “heir”). Either way, it should be clear that the king’s eldest son will die. It may be easier to follow Good News Translation‘s “heir to the throne,” but if the word “heir” implies that the king has already died, one may say “who is due to sit on his father’s throne” or “who will rule after the king [or, his father] dies.” The ambiguity is not so easily resolved, however, in view of 12.29, where the same phrase is used in reference to the actual death of the king’s son, after it happened rather than before. (See the comment there.) Therefore it is better to follow Revised Standard Version and others in understanding who sits upon his throne to refer to the king himself. Durham has “from the firstborn of Pharaoh, the occupant of the royal throne,” and Revised English Bible simply says “from the firstborn son of Pharaoh on his throne” (similarly New American Bible). Contemporary English Version omits the phrase entirely, with “Your own son will die.”

Who is behind the mill refers to any maidservant, or “slave woman” (Good News Translation), who had to sit or kneel and grind out the grain. The mill, or “handmill” (New Revised Standard Version), consisted of two stones, the smaller one held in both hands and used for grinding into flour the grain that was placed on the larger flat stone. Behind the mill simply refers to the physical position required of the “servant-girl who grinds with the hand-mill” (Durham). In referring to “the slave woman,” Moses is showing that the firstborn sons of all slaves, even the ones lowest on the scale, would die. So one may translate “the son of the lowest slave woman” (Contemporary English Version).

And all the first-born of the cattle refers to the male offspring of the domesticated animals owned by the Egyptians. The word for cattle is a general term, so “livestock” (New Revised Standard Version, New Jerusalem Bible) is a better choice. Other ways of saying this are “the firstborn males of the Egyptian cattle will die” or “the firstborn males of the Egyptian domesticated animals will die.”

An alternative translation model for verses 4 and 5 is:

• Moses went to the king and said, “Yahweh says that about midnight he will go through the land of Egypt. Wherever he goes, the firstborn son in every Egyptian family will die. Your own son will die, and so will the son of the slave woman who grinds the grain. Even the firstborn male of all the domesticated animals will die.

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .