Amr bin Shu'ayb narrates from his father, who narrates from his grandfather, that the Prophet (peace and blessings be upon him) said: "Whoever kills deliberately is to be handed over to the heirs of the slain person; if they wish they may kill him, and if they wish they may take the blood money, which is 30 hiqqah, 30 jadha'ah and 40 pregnant she-camels. That is the blood money for deliberate killing; whatever they settle on is theirs, and that is the aggravation of the blood money." And the Messenger of Allah (peace and blessings be upon him) said: "The blood money for quasi-deliberate killing is aggravated like the blood money for deliberate killing, but its perpetrator is not killed. That is when Satan stirs up trouble among people and there is blind fighting with stones, without any rancour and without carrying weapons."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16129