Tawus said: An angel was sent to the Prophet (peace and blessings be upon him) whom he (peace and blessings be upon him) did not recognise. He said: "Your Lord Almighty gives you the choice between being a Prophet who is a servant or a Prophet who is a king." Jibril (peace be upon him) gestured to him to adopt humility. He (peace and blessings be upon him) said: "I want to be a Prophet who is a servant."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13321