I am no expert, but I think that I can answer this out of general knowledge.
First of all, Mohammad was not the first to oppose representations of god. The depiction of a god leads all too easily to idol worship. I doubt that you would find any depiction of god that was sanctioned by Jewish religious leaders, although you will find a lot of references in the Old Testament to the ancient Israelites tearing down the idols of others. During the early decades of Christianity, too, there was a good deal of fear that icons would have the effect of drawing people perilously close to the worship of painted representations of god and the saints. There were two periods in the history of Byzantium when the religious authorities, backed up by the emperor, tried to ban icons. Look up "iconoclast" in Wikipedia for more information on this. However, Christianity soon reached a degree of comfort with the idea of representing god, Jesus, saints, etc. Sometimes, indeed, it is hard not to feel that the line into superstition, even idol worship, had been crossed. For example, in the Russian Orthodox church, there are icons of icons: that is, icons that represent the various miracles attributed to famous icons like the Virgin of Vladimir. The Chistian penchant for believing that icons and holy relics would bring victory in battle was a joke to the Moslems during the Crusades, when once a Christian army was defeated and lost the piece of the "true cross" that they had put their faith in. The Christians had to pay a hefty ransom to get it back.

I would be interested in this question: In one book, I read that Muhammad had himself buried in an unknown location so that his grave might never become the site of worship and lead his followers into a near-idolotrous veneration for him. In another book, I read that Muhammad's grave, and the graves of many of his family, were purposely destroyed by the Sunni in order that they might not become a source of temptation, and that to this day, the Saudi religious police prevent the Shia, who do venerate religious figures in this way, from going into the area where the graves were. Which is right?

I think both are correct.i read them both in one book,but i am not totally sure so i asked this question here in absolute astronomy so that i can choose and think or do have an idea for why muhammad oppose the creation of symbols and icons.

I have found the passage in one book, saying that Muhammad had a grave in Medina and that it was destroyed by more fundamentalist Muslims in order to prevent it from becoming an object of idolatrous veneration by less-strict Muslims. This is from "The Shia Revival," by Vali Nasr, pages 96-97:

“Wahabism emerged in the Arabian peninsula as a “back to the roots of Islam” reform movement in the nineteenth century. Its base of power was in the oases hat dotted the barren landscape of the desert of Nejd, the interior plateau egion that is also the seat of the House of Saud, the princely ruling clan of today’s Saudi Arabia. Abdul Wahab was a purist. His creed reflected the simple ways of the desert tribesmen of Nejd, natives of what was then a fringe region of the Islamic world. He sought to cleanse Islam of all he cultural practices that it had borrowed and incorporated over the centuries. They had corrupted and weakened Islam, he said, and must be purged. Following the example of Ibn Taymiya, he rejected anything other than a literal reading of the Quran and the prophetic traditions.

“Wahabism rejected the notion of any mediating authority between man and God as untrue to the original essence of Islam. Even the Prophet was seen as a mere messenger of God, the equal of all other mortals and undeserving of any special veneration. In 1804, Abdul Wahab’s sentinels burst out of the desert into the holy city of Medina and made a show of their zeal by destroying the Prophet’s tombstone in order to stop their fellow Muslims from 'worshipping' it.

“Wahabis condemned the veneration of saints and their shrines as polytheism and viewed Muslims who engaged in this action as heretics. Before setting their eyes on the Prophet’s mosque, in 1802, Wahabi armies had invaded Karbala and desecrated the shrine of Imam Husayn – an event that has left and indelible mark on Shia historical memory. The Wahabi conquest of the Arabian peninsula involved violence against the Shia. In 1913 the fanatical Ikhwan (Brotherhood) army of the Wahabi commander (and later first king of Saudi Arabia) Abdul-Aziz Ibn Saud invaded the Shia region of al-Hasa and tried to impose Wahabism on the population. In 1925 Ibn Saud’s forces destroyed the cemetery of Jannat al-Baghi (Tree Garden of Heaven) in Medina, where the Prophet’s daughter and the second, fourth, fifth, and sixth Shia imams were buried. To this day, during hajj Shia pilgrims sneak off to the site of Jannat al-Baghi to pray – that is, if they can escape the canes of Saudi Arabia’s morality police, the feared mutawaeen.”

I cannot, at the moment, find the book that said that Muhammad had himself buried secretly by his closest followers in order to prevent Muslims from turning him into the object of worship. It was probably "Muhammad. Messenger of God" by Betty Kelen.

Oh yeah i got it now.maybe i can search for it on the book that you mean.i'll look for it to get the answer.i have a bit idea now about the things you said.thank you for yor help. i really need it.take care.