The prohibition against murder is among the most fundamental moral principles in all of human civilization. Its source is the divine declaration that every person is created b'tzelem Elohim — in the image of God. To destroy a human life is therefore not merely a crime against a person, but an act against the Divine image in the world.
The Talmud captures this with striking force: whoever saves a single life, it is as if he saved an entire world. And whoever destroys a single life, it is as if he destroyed an entire world (Sanhedrin 37a). Every person carries within them a universe of potential — relationships, creativity, memory, and irreplaceable worth.
This law encompasses not only direct killing but extends to endangering life through negligence, withholding aid from someone in mortal danger, and other forms of causing death. A just society is built on the conviction that no human being may be arbitrarily deprived of life.
The prohibition of murder was renewed with Noah after the flood, grounding it in a universal covenant: whoever sheds the blood of man, by man shall his blood be shed; for in the image of God He made man (Genesis 9:6). The verse is both the law and its reason.