﴿ مِنْ أَجْلِ ذَٰلِكَ كَتَبْنَا عَلَىٰ بَنِىٓ إِسْرَٰٓءِيلَ أَنَّهُۥ مَن قَتَلَ نَفْسًۢا بِغَيْرِ نَفْسٍ أَوْ فَسَادٍۢ فِى ٱلْأَرْضِ فَكَأَنَّمَا قَتَلَ ٱلنَّاسَ جَمِيعًۭا وَمَنْ أَحْيَاهَا فَكَأَنَّمَآ أَحْيَا ٱلنَّاسَ جَمِيعًۭا ۚ وَلَقَدْ جَآءَتْهُمْ رُسُلُنَا بِٱلْبَيِّنَٰتِ ثُمَّ إِنَّ كَثِيرًۭا مِّنْهُم بَعْدَ ذَٰلِكَ فِى ٱلْأَرْضِ لَمُسْرِفُونَ ﴾

“Because of this did We ordain unto the children of Israel that if anyone slays a human being-unless it be [in punishment] for murder or for spreading corruption on earth-it shall be as though he had slain all mankind; whereas, if anyone saves a life, it shall be as though he had saved the lives of all mankind. And, indeed, there came unto them Our apostles with all evidence of the truth: yet, behold, notwithstanding all this, many of them go on committing all manner of excesses on earth.”

it shall be as if he had slain mankind altogether, because every individual [human] entails what is entailed by every individual of that species, for a species subsists in the one as it subsists in all outwardly and number has no bearing in this respect, for a species is not augmented in reality by the number of its individuals nor is it diminished by its being restricted to the one.