مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3832
Musnad of Abdullah bin Mas'ood
It was narrated from ‘Abdullah (رضي الله عنه) that The Prophet (ﷺ) said to a man: "Were it not that you are an envoy, I would have killed you.”
Musnad Ahmad 3855A saheeh hadeeth; this is a hasan isnad]