The messenger of Musaylimah came to the Prophet ﷺ, and the Prophet ﷺ asked him, "Do you bear witness that I am the Messenger of Allah?"He replied with something, and the Prophet ﷺ said to him, "Were it not that I do not kill messengers," or, "Had I ever killed a messenger, I would have killed you."
حدثنا أسود بن عامر أنبأنا شريك عن أبي إسحاق عن صلة
أن رسول مسيلمة أتى النبي ﷺ فقال له أتشهد أني رسول الله فقال له شيئا فقال له النبي ﷺ لولا أني لا أقتل الرسل أو لو قتلت أحدا من الرسل لقتلتك
No references are available.
Its isnad is sahih. Silah is Ibn Zafar Absi, a trustworthy taabi, and he was deemed trustworthy by Shubah, Ibn Main, and others. The hadith is an abridgment of 3761 and 3837.