Musannaf Ibn Abi Shayba 18:1089

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Isra’il narrated to us, from Abu Ishaq, from al-Harith ibn al-Azma’, who said: A slain person was found in Yemen between [the tribes of] Wada’ah and Arhab. The governor of ‘Umar ibn al-Khattab wrote to him [‘Umar], and ‘Umar wrote back to him: "Measure the distance between the two tribes, and whichever of them he was closer to, hold them responsible for him." He said: So they measured and found him closer to Wada’ah. He said: So we were held responsible and we were fined, and we were made to take an oath. We said: "O Commander of the Faithful, do you make us take an oath and [also] fine us?" He said: "Yes." He said: So fifty men from among us were made to swear by Allah that they did not do it, nor did they know the killer.