مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3618
Musnad of Abdullah bin Mas'ood
It was narrated that Harithah bin Mudarrib said: ‘Abdullah (رضي الله عنه) said to Ibn an-Nawwahah: I heard the Messenger of Allah (ﷺ) say: "Were it not that you are an envoy, I would have killed you." (Abdullah continued:) But today, you are not an envoy; O Kharashah, get up and strike his neck.” So he got up and struck his neck.
Musnad Ahmad 3642A saheeh hadeeth]