A Hindu has approached me recently and queried the Qur'an's teachings. He has said that the Qur'an originated from the Hindu books known as the 'Vedas', which he claims were written thousands of years before Islam. Further still he claims the Hinduism is the first and foremost religion. Though I have endeavored to find a suitable answer for his queries I do not have enough knowledge to answer him in full. Hence please could you advise on the matter. I realise that Hindu's are Kufr (due to their idol worshipping) among other defects in their religion, however how can I disprove what he is saying?

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
A rational person can not deny that Islam is a true religion and no one can doubt the truthfulness of the Prophet Muhammad (Peace and blessing be upon him).
Everyone who denies this fact whether a Hindu or else denies it out of hatred to Islam refusing to accept the truth. They, i.e. non-Muslims, turn away from Islam after believing that Islam is a true and a comprehensive religion, its teachings suit all mankind.
We would demand them to refer to their so-called holy books leaving what Muslims believe. We find in Prati Sarg Paru of Bhavisha Purana (a book from the Puranas), the following passage:
"A "malechha" [belongs to a foreign country and speaking a foreign language] spiritual teacher will appear with his companions. His name will be Muhammad. "Raga" after giving this "Maha Dev Arab" [Arab of Angelic character] a bath in the Panchgavya and the Ganges water [and thus purging his sins] offered him the presents of his sincere devotion and showing him all reverence said, 'I make obeisance to thee. ' 'O ye the pride of mankind, the dweller in Arabia, you have collected a great force to kill the Devil and you yourself have been protected from the "malechha's" opponents.' 'O ye! The image of the Most Pious God the biggest Lord, I am a slave to thee, take me as one lying on thy feet.' (prati Sarg Parv III: 3, 3.5-8)
This prophecy indicates the following points:
1. The name of the Prophet is clearly stated as Muhammad.
2. He is said to be from Arabia. The Sanskrit word "marusthal" used in the Prophecy means a sandy tract of land or desert.
3. Special mention is made of the companions of the Prophet. Indeed, his companions reflected many of the qualities he himself had.
4. He will be immune from sins, having an angelic character.
5. The Raja of India will treat him with honor and deference.
6. The Prophet will be granted protection from his enemies.
7. He will kill the Devil, root out idol-worship and will do away with all sorts of vices.
8. The Maharishi claims to be lying at his feet.
9. He is regarded as the "pride of mankind" (Parabatis Nath)
We can see that Hindu scripture also give faithful descriptions of Prophet Muhammad. The revelation of the Qur'an and the prophethood of Muhammad are signs and guidance from God for mankind as a whole. In the Qur'an, God Almighty constantly refers to Muhammad in universal terms: "The Seal of the Prophethood," "Mercy to all the Worlds," "Beginner of Glad Tidings" and a "Messenger of God." If we compare the teachings of Muhammad with those of other Prophetic faiths-Judaism, Christianity and Zoroastrianism, we see commonality. However, as Muhammad was to be the last Prophet, it would only seem natural that he should be universal. It is because this-that Muhammad is God's instrument of guidance for the world-that he has been mentioned in many of the previous revelations.
No doubt even though the holy books of Hindus contain myths, superstitution, polytheism and many null matters, the above quoted sentence clearly proves that Muhammad (Peace and blessing be upon him) has been mentioned in many of their books. This fact is made clear in Qur'an. Allah Says (interpretation of meaning): {And verily, it (the Qur'ân, and its revelation to Prophet Muhammad SAW) is (announced) in the Scriptures [i.e. the Taurât (Torah) and the Injeel (Gospel)] of former people.}[26:196].
How could it be imagined that the Prophet derived Islam, the religion based upon monotheism from the Hinduism, the religion which teaches polytheism, idolship and myths and superstition. Everyone knows that Prophet Muhammad (Peace and blessing be upon him) was "Ummi" illiterate who could neither read nor write, how could such person make the ancient books and religions a source to form a new religion. This is a very silly allegation to the Prophet Muhammad (Peace and blessing be upon him) who has been accused of this matter before. The Kuffar of Makkah accused him of taking his religion from Jews and Christians. Allah Says (interpretation of meaning): {And they say: "Tales of the ancients, which he has written down, and they are dictated to him morning and afternoon." Say: "It (this Qur'ân) has been sent down by Him (Allâh) (the Real Lord of the heavens and earth) Who knows the secret of the heavens and the earth. Truly, He is Oft-Forgiving, Most Merciful."}[25:5-6].
Imam Ibn Katheer and others say that this allegation is so silly, and ridiculous that everyone rejects it. They the Kuffar of Makkah knew him from his birth till he became Prophet. All of the inhabitants of Makkah witnessed him grew up; his child hood, his youth, and adulthood, they surely had the knowledge that Prophet did not learn to read or write, he never received any education at all from a living being. They testified of his truthfulness, virtuousness, faithfulness honesty, etc., till they called him "Amen" (the trustworthy) "Sadiq" (the truthful) even before his prophecy. When he was sent to them as Prophet, they turned against him and accused him of many falsities. Every normal person knows that he is far from all these allegations.
We would like to ask every non-Muslim to compare between the Qur'an and those books which he believes are holy ones. One could then easily finds the clear distinguishing features between the Words of God and the words of creatures. The teachings of Islam are good, comprehensive, useful for all mankind and suitable for all times while the teachings of other religions are not so. The Prophet was born orphan, did not attend school in his life. He pastured sheep in his child hood. He was raised in the desert among Bedouins. He never lived outside Makkah before he became Prophet. Despite of all these facts they accused him of taking from old scriptures when he tried to guide them to the true path. There are many books written in Arabic and other languages that contain a lot of evidence, proving the truthfulness of the Prophet Muhammad (Peace and blessing be upon him).
Allah knows best.