And he said to them introduces what Moses said to the Levites. Thus says the LORD God of Israel is identical with the messenger formula used in 5.1. (See the comment there and at 4.22.) This formula introduces the exact word of Yahweh as a quote within a quote. Both Good News Translation and Contemporary English Version have “The LORD God of Israel commands….” Put every man his sword on his side is literally “You [plural] place a man his sword upon his upper thigh.” The word for sword probably refers to a long dagger, about eighteen inches in length, with a straight double-edged metal blade and a wood or bone handle. It was carried in a leather sheath tied to the girdle and worn at the left side. In certain languages this sentence will be expressed as “tie your sword to your belt.”

And go to and fro from gate to gate throughout the camp is literally “you [plural] pass through and you return from gate to gate in the camp.” Good News Translation assumes there were two gates, “from this gate to the other.” Durham assumes there was only one, “from the entrance and back again.” New International Version does not use gate but has the intended meaning, “from one end to the other.” The word for go means to pass through from one side to the other.

And slay every man his brother, literally “and you [plural] kill a man his brother,” uses the common word for “kill” (Good News Translation), as in verse 12. (See the comment at 2.14.) The word for brother in this context refers broadly to the fellow tribesman and even the fellow Israelite. It does not include women, however, and in certain languages it will be necessary to make this explicit; for example, “kill your male relatives, friends, and neighbors.” His companion includes friend, fellow, or comrade. His neighbor uses a word for someone very close, in terms of either space or kinship. So the three terms overlap in meaning. The point is that the Levites were to spare no one who presumably had been guilty of worshiping the golden calf.

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 .