dr. jan lake says in his book (the arabs):

“the historic life of muhammad (peace be upon him) cannot be described using any words that are better than what allah (the almighty) says in a few words through which he mentions the reason of the prophet’s (peace be upon him) mission saying: “and in no way have we sent you except as a mercy to the worlds“. (surat al- anbiya (the prophets) 107). moreover, the prophet has proved by himself that he has the greatest mercy for every weak, and every one who needs help. muhammad (peace be upon him) was a true mercy for all of the orphans, poor, wayfarers, fate-stricken, weak, workers and the people of pains and trouble. i, with love and longing, ask allah for prayers to be upon him and his companions.