It is narrated from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that a messenger from Musaylimah the Liar came to the Prophet (peace and blessings be upon him). The Prophet (peace and blessings be upon him) asked him: "Do you testify that I am the Messenger of Allah?" He replied: "We testify that Musaylimah is the Messenger of Allah." The Prophet (peace and blessings be upon him) said: "If I were to kill messengers, I would have beheaded both of you."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 3851
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد ضعيف لضعف شريك بن عبدالله النخعي.