Quran ch :5 v32.If anyone killed a person not in retaliation of murder, or (and) to spread mischief in the land - it would be as if he killed all mankind, and if anyone saved a life, it would be as if he saved the life of all mankind.
Blood Money (Ad-Diyat) [83:10] Narrated Anas bin Malik: The Prophet said, "The biggest of Al-Kaba'ir (the great sins) are (1) to join others as partners in worship with Allah, (2) to murder a human being, (3) to be undutiful to one's parents (4) and to make a false statement," or said, "to give a false witness."
*"The first cases to be adjudicated between people on the Day of Judgment will be those of bloodshed [killing and injuring] "-Mohammad,Narrated in Saheeh Muslim, #1678, and Saheeh Al-Bukhari, #6533.
Qur'aan Ch : 3 verse 186. You shall certainly be tried and tested in your wealth and properties and in your personal selves, and you shall certainly hear much that will grieve you from those who received the Scripture before you (Jews and Christians) and from those who ascribe partners to Allâh; but if you persevere patiently, and become Al-Muttaqûn (the pious - See V.2:2) then verily, that will be a determining factor in all affairs (and that is from the great matters which you must hold on with all your efforts).
Ch : 2 verse 2
This is the Book (the Qur'ân), whereof there is no doubt, a guidance to those who are Al-Muttaqûn [the pious and righteous persons who fear Allâh much (abstain from all kinds of sins and evil deeds which He has forbidden) and love Allâh much (perform all kinds of good deeds which He has ordained)].