Jesus and Muhammad lived quite different lives in different circumstances and different centuries. So, information, about the lives of each, must be sought from entirely different sources.
The gospel stories are the only known sources that may provide any information about the life of Jesus. There are several gospels, of which four are in the New Testament, while modern Christianity regards the remaining gospels as in error. The four canonical gospels are those of Matthew. Mark, Luke and John.
Many scholars regard Mark's Gospel as the first gospel to be written. They say that it was probably written around 70 CE, about 40 years after the death of Jesus. Some scholars also say that the other gospels were based on Mark's Gospel, thus making Mark's Gospel the original source from which all other histories of Jesus were based. Matthew and Luke contain additional sayings, believed by scholars to be from a sayings source now called the 'Q' document, but when they reported the same saying, each evangelist placed that saying by Jesus in a completely different context and time. For its part, John's Gospel sometimes contradicts the other gospels.
Thus, a search for the history of Jesus should perhaps be based on Mark's Gospel.
Muhammad was a businessman or merchant, before he began his mission to spread Islam. In Mecca, Muhammad remained monogamous, married only to Khadija, even though polygamy was common in Arabia. Eventually, Muhammad had to flee to Medina, where he became a great sayyid (chief ) and married several wives, mainly for political reasons. Unlike the Bible, with its gospel histories of Jesus, the Koran does not really contain a history of Muhammad, so a more detailed account must be obtained from other sources.