Musannaf Ibn Abi Shayba 18:847

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Al-A’mash narrated to us, from Zayd ibn Wahb, he said: A man saw a man with his wife, so he killed her. He was brought before Umar, and some of her brothers gifted their share [of the blood money/retribution] to him. Umar ordered the rest of them to take the blood money.