Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī

Killing one person unjustly is like killing all of humanity; Saving one person is like saving the entire humanity

quran:5:32 –

Because of that, We decreed upon the Children of Israel that whoever kills a soul unless for a soul or for corruption ˹done˺ in the land - it is as if he had slain mankind entirely. And whoever saves one - it is as if he had saved mankind entirely. And our messengers had certainly come to them with clear proofs. Then indeed many of them, ˹even˺ after that, throughout the land, were transgressors.  

Because of that, which Cain did, We decreed for the Children of Israel that whoever slays a soul for other than a soul, slain, or for, other than, corruption, committed, in the land, in the way of unbelief, fornication or waylaying and the like, it shall be as if he had slain mankind altogether; and whoever saves the life of one, by refraining from slaying, it shall be as if he had saved the life of all mankind — Ibn ‘Abbās said ˹that the above is meant˺ in the sense of violating and protecting its ˹a soul’s˺ sanctity ˹respectively˺. Our messengers have already come to them, that is, to the Children of Israel, with clear proofs, miracles, but after that many of them still commit excesses in the land, overstepping the bounds through disbelief, killing and the like.
القرآن:٥:٣٢ –

مِنْ أَجْلِ ذَٰلِكَ كَتَبْنَا عَلَىٰ بَنِي إِسْرَائِيلَ أَنَّهُ مَنْ قَتَلَ نَفْسًا بِغَيْرِ نَفْسٍ أَوْ فَسَادٍ فِي الْأَرْضِ فَكَأَنَّمَا قَتَلَ النَّاسَ جَمِيعًا وَمَنْ أَحْيَاهَا فَكَأَنَّمَا أَحْيَا النَّاسَ جَمِيعًا ۚ وَلَقَدْ جَاءَتْهُمْ رُسُلُنَا بِالْبَيِّنَاتِ ثُمَّ إِنَّ كَثِيرًا مِنْهُمْ بَعْدَ ذَٰلِكَ فِي الْأَرْضِ لَمُسْرِفُونَ  

{من أجل ذلك} الذي فعله قابيل {كتبنا على بني إسرائيل أنه} أي الشأن {من قتل نفسا بغير نفس} قتلها {أو} بغير {فساد} أتاه {في الأرض} من كفر أو زنا أو قطع طريق أو نحوه {فكأنما قتل الناس جميعا ومن أحياها} بأن امتنع عن قتلها {فكأنما أحيا الناس جميعا} قال ابن عباس: من حيث انتهاك حرمتها وصونها {ولقد جاءتهم} أي بني إسرائيل {رسلنا بالبينات} المعجزات {ثم إن كثيرا منهم بعد ذلك في الأرض لمسرفون} مجاوزون الحد بالكفر والقتل وغير ذلك.