God instructed Israel about what to do when a man was killed. These verses show that God recognizes only two classifications of killing: accidental and intentional. "Self-defense" is not even listed as a possibility! God illustrates "accidental death" as occurring when there is no intent to kill or to harm. It is accidental when there is no awareness that an action will result in the death of another. Deuteronomy 19:5 provides a clear example of such an accident: ". . . as when a man goes to the woods with his neighbor to cut timber, and his hand swings a stroke with the ax to cut down the tree, and the head slips from the handle and strikes his neighbor so that he dies."
However, when there is intent to kill or injure, God's law defines it as murder regardless of what the other person was threatening to do, about to do, or in the process of doing. If a man fires a gun with the foreknowledge that it has the potential to kill another man, it is murder. The "self-defense" category is something afforded by the law of the land, not by the law of God.
David C. Grabbe
Does Scripture Allow for Killing in Self-Defense?
The cities of refuge were sanctuaries to which those who accidentally killed another could flee. There were six of them located throughout Israel, three on each side of the Jordan River. Even if the killer made it to a city of refuge, he still had to undergo a trial. If he was found guilty of committing an accidental death, he had to remain in the city until the death of the current high priest. Thus, the city served as his jail. However, he was otherwise free to move about, find employment, and live with and support his family.
If he left the city for any reason, the avenger of blood could lawfully take the killer's life. The avenger of blood (verses 12, 19) was usually a blood-relative of the manslaughter victim. His assignment from the family was to protect the family's rights and to avenge the family's loss of the killed person. The vengeance taken was not always to take the killer's life. If the avenger actually took the killer's life before he managed to reach a city of refuge, then he truly was an "avenger of blood." However, the Hebrew term translated "avenger" is go'el, which has fascinating ramifications when appearing in other contexts, as it can also be translated "redeem" or "redeemer."
In the book of Ruth, it is translated as "redeem" seven times. Boaz was Ruth's redeemer. The redeemer was the one who stood for his family in order to protect its rights. Boaz protected the rights of his family in behalf of Ruth and Naomi due to Naomi's husband's death. He was the family's "avenger."
John W. Ritenbaugh
The Sixth Commandment
Under the original letter of the law, it was intentional killing (murder) that was forbidden. Accidental killing was not regarded as murder. Nevertheless, manslaughter is a horrible crime, and the culprit had to remain in a city of refuge until the high priest died.
Martin G. Collins
The Sixth Commandment
Other Forerunner Commentary entries containing Numbers 35:9: