A glance at Qur'anic verses shows Prophet's covenant on prophetic mission, and that he was commanded to be patient where the Holy Qur'an says: "And [mention, O Muhammad], when We took from the prophets their covenant and from you and from Noah and Abraham and Moses and Jesus, the son of Mary; and We took from them a solemn covenant." (Ahzab:7) and "So remain on a right course as you have been commanded, [you] and those who have turned back with you [to Allah ], and do not transgress. Indeed, He is Seeing of what you do." (Hud: 112)
Therefore, the Prophet (PBUH) had been perseverant in open proclamation of the religion of Allah and he had not transgressed those who had turned their back to the religion. "And when Our verses are recited to them as clear evidences, those who do not expect the meeting with Us say, "Bring us a Qur'an other than this or change it." Say, [O Muhammad], "It is not for me to change it on my own accord. I only follow what is revealed to me. Indeed I fear, if I should disobey my Lord, the punishment of a tremendous Day." (Yunis: 15)
The Messenger of Allah did not neglect carrying out his mission out of personal fear or for some other problems such as the story of Zayd's wife Zeinab indicates: "So when Zayd had no longer any need for her, We married her to you in order that there not be upon the believers any discomfort concerning the wives of their adopted sons when they no longer have need of them. And ever is the command of Allah accomplished," (Ahzab: 37) or the story of the revivification of the believers indicates: "O you who have believed, do not enter the houses of the Prophet except when you are permitted for a meal, without awaiting its readiness.
source : www.tebyan.net