Praise be to Allah (The Glorified and Exalted)
Yes, the hadith are an important aspect of Islam and must be followed.
1) Due to the manner in which the Qur'an was revealed, making it short, eloquent, and melodious in recitation, the Almighty did not reveal every aspect of His "religion" more specifically "way of life" in which He wants humans to live by, entirely by the Qur'anic revelation. Instead, the Almighty states within the Qur'an that people must refer to His prophet for further instruction. This is called the Sunnah (tradition or example of the Prophet), which is contained in the "Six Books" of hadith (sayings) or accounts. The "Six Books" are the following:
Bukhari, Muslim, Abu Dawud, Tirmidhi, Nisaa’i, and Ibn Majah. Of which Bukhari and Muslim are considered Sahih (Authentic sayings or accounts), meaning all of them come from the Prophet (peace and blessings of Allah be upon him). The other books are a mixture and may have some hadith that are weaker to prove that they came from the Prophet (peace and blessings of Allah be upon him).
There are also other notable scholars (may Allah have mercy on them), such as Ahmad, from whose books the Sunnah may be learned.
The hadith are graded, the highest rating is "golden chain of transmission." This means that this account did come from the Prophet (peace and blessings of Allah be upon him) 100%. All of the hadith or accounts are passed by narrators, all of their names and biographies are well known. They were not private, but rather publicly known individuals that were known to be pious and knowledgeable. If it is considered that there is a problem in the chain of narrators, then the Hadith or accounts lose some credibility and those are ranked lower, such as "weak" known as "
da'eef" in Arabic, and some may be considered lies or "false accounts."
Go to the following site and read their analysis on a certain hadith:
http://islamqa.com/en/ref/2534
2) In Islam, we believe that Allah (The Glorified and Exalted) will keep the practice of His religion on the Earth until the Day of Resurrection, by inspiring different persons to support His religion. This is done in various ways: The Almighty gives the individual a kind of personality type in which the individual possesses a great deal of wisdom and insight in his understanding, he understands human nature (i.e. he understands how some humans speak and behave and can anticipate what they would or would not do), he has been blessed with a photographic memory and can memorize a great deal of information, the Almighty will give him a strong inclination to religiosity, keep his character clean, and his intentions pure, the Almighty will also expose the individual to other learned men, so that this person will grow as a "scholar" in terms of knowledge and understanding of Islam. It is also the case that
no other prophet will be sent to mankind before the Day of Judgment. Therefore, the Creator is going to keep the Qur'an and Islam in its puritan form up to the Day of Judgment, because He is going to use it as evidence by which He will judge everyone that came after the final Prophet (peace and blessings be upon him). Therefore, the Almighty is not going to allow the majority of the Muslims to become misguided, because people will then complain that they can not be judged because heretics were larger in terms of their numbers. The majority of the people that call themselves "Muslims," and the scholars of the religion, follow the Qur'an and Sunnah (from hadith and accounts), which the Prophet (peace be upon him) told them to do. This is how Islam has been preserved through the ages by the promise of Allah (The Glorified and Exalted).
3) It is also the case that the hadith
were not written over 200 years after the Prophet (peace and blessings be upon him). For example, Ali (may Allah be pleased with him) had a scroll with some things the Prophet (peace be upon him) had mentioned to him. Other people may have had similar things and written down accounts, this is how the narrations were preserved. People also passed them down by oral tradition and individuals preserved the Sunnah (example of the Prophet) through example in every day life. It just happens that Bukhari (may Allah have mercy on him), a man chosen by Allah as mentioned above that some humans are chosen for this purpose, wrote his famous collection of hadith or accounts in a single book many years later. However, there are plenty of other accounts outside his Book that are also authentic as graded by other scholars. Bukhari (may Allah have mercy on him) simply found the hadith that were available to him during his time period and travels, and some he may have not accepted due to the individual that narrated it to him, perhaps he did not trust the judgment of that individual or the chain of narrators that were recorded, because the same hadith may also have other chain of narrators. This is why in his book, he mentions the same hadith by various different chains. The more accounts the better.
4) Due to its complexity, this is a topic for a student of religion within a university. A common Muslim must simply know that they must follow
both Qur'an and hadith, in order to gain salvation.
And Allah (The Exalted) Knows Best.