Negative commandment · Lo Ta’aseh #289 of 613
Not to kill an innocent person
שלא להרוג נקי
The verse · Shemot 20:13
לֹא תִּֿרְצָח לֹא תִּֿנְאָף לֹא תִּֿגְנֹב לֹא־תַעֲנֶה בְרֵעֲךָ עֵד שָׁקֶר
“Thou shalt not murder. Thou shalt not commit adultery. Thou shalt not steal. Thou shalt not bear false witness against thy neighbour.”
The Rambam’s words
Not to kill an innocent person, as [Exodus 20:13] states: "Do not murder."
שלא להרוג נקי, שנאמר "לֹא תִּרְצָח" (שמות כ, יב; דברים ה, טז).
Why · Sefer HaChinuch #34
To not kill the innocent
“The root of this commandment is well-known and revealed to all that see the sun. As G-d, may He be blessed, created the world and commanded us be fruitful and multiply, in order to settle it in front of Him.”
Who & when
“And [it] is practiced in every place and at all times by males and females.”
Where in the Mishneh Torah
Hilchot Murderer and the Preservation of Life הלכות רוצח ושמירת נפש