Musannaf Ibn Abi Shayba 38:131

Ibn Numayr narrated to us, he said: Ubaydullah ibn Umar narrated to us, from Nafi’, who said: When Ibn Umar heard that Najdah had approached, and that he intended to come to Medina, and that he was taking women captive and killing children, he said: "If so, we will not leave him." He was determined to fight him and incited the people. It was said to him: "The people will not fight with you, and we fear that you will be left alone." So he left him.