The source is Jewish, Sanhedrin 4:5:
...for we find concerning Cain who killed his brother, it is written, "the bloods of your brother cry" (Genesis 4:10); it does not say, "your brother's blood" but "bloods" - his blood and the blood of his offspring.
Another interpretation of "brother's bloods" - his blood was dashed on the trees and on the stones. Therefore man was created singly, to teach you that whoever destroys a single soul of Israel, Scripture accounts it as if he had destroyed a full world; and whoever saves one soul of Israel, Scripture accounts it as if he had saved a full world. And for the sake of peace among men, that one should not say to his fellow, "My father is greater than yours;" and that heretics should not say, "There are many powers in Heaven." Again, to declare the greatness of the Holy One, blessed be He, for man stamps out many coins with one die, and they are all alike, but the King, the King of kings, the Holy One, blessed be He, stamped each man with the seal of Adam, and not one of them is like his fellow. Therefore each and every one is obliged to say, "For my sake the world was created." And lest you say, "What do we need with this trouble?" Has it not already been said, "He being a witness, whether he has seen or known, if he does not utter it..." (Leviticus 5:1). And should you say, "What need is there for us to be
responsible for the blood of this one?" Surely it is said, "And when the wicked perish, there is joy" (Proverbs 11:10).
Dr. Andrew Bostom wrote:
Immediately following the murderous acts of jihad terrorism committed on September 11, 2001, Ibn Warraq highlighted the tragic irony of many apologists quoting selectively from Qur’an 5:32-“whoso slays a soul . . . shall be as if he had slain mankind altogether; and whoso gives life to a soul, shall be as if he has given life to mankind altogether”- attempting to demonstrate that the Qur’ran disapproved of violence and killing.
Firstly, these wonderful sounding words come from a preexisting Jewish text (Mishnah, IV Division 5), “Thus was created a single man, to teach us that every person who loses a single soul, it shall be written about him as if he has lost the entire world, and every person who sustains a single soul, it shall be written about him as if he has sustained the entire world.”
And apologists for Islam-just like President Obama-quote the Koranic words out of context. For the very next verse offers quite a different meaning from that of 5:32, which was “laid…down for the Israelites,” as stated in verse, 5:33, continuing:
“…Our apostles brought them [the Jews] veritable proofs: yet it was not long before many of them committed great evils in the land. Those that make war against Allah and His apostle [Muhammad] and spread disorder shall be put to death or crucified or have their hands and feet cut off on alternate sides, or be banished from the country. (Qur’an 5:33)”