Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) said that among the judgments of the Messenger of Allah (peace and blessings be upon him) is the judgment on the major diyah; then he likewise mentioned the minor diyah. Then he said: "Camels are becoming scarce and expensive." So Sayyiduna Umar (may Allah be pleased with him) fixed 6000 dirhams, at the rate of one and a half uqiyah per camel. Then camels again became expensive and dirhams cheap, so Sayyiduna Umar (may Allah be pleased with him) added 2000, at the rate of 2 uqiyahs per camel. Then camels again became expensive and dirhams cheap, so he (may Allah be pleased with him) fixed 12000 dirhams, 3 uqiyahs for each camel, and he added a further third of the diyah for the sacred month and a further third for the sacred city, so that altogether the diyah came to 20000. And he said: "If they are Bedouins, the diyah is to be taken from their livestock, and from every people the diyah is to be taken from the wealth current among them, with fairness."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16172