Allah ta'ala sent the Prophet salallaho alaihe wasallam with a mission that He has explained in His holy book:
Allah did bestow a great favor on the believers when He sent among them a messenger from among themselves, rehearsing unto them the Signs of Allah, purifying them, and instructing them in Scripture and the Wisdom, while, before that, they had been in manifest error (3:164)
All four missions of the Prophet salallaho alaihe wasallam will remain until the Day of Judgment. Allah ta'ala has informed us that He will preserve His book that was given to the Prophet salallaho alaihe wasallam, the wordings of it, and the recitation. It is vital that the meanings must be preserved, so that it is understood in the manner that Allah ta'ala wants it to be, and this is achieved through the preservation of the wisdom (sunnah of the Prophet salallaho alaihe wasallam ). In order to implement this in our lives, the individual must have sincerity and struggle towards purification of the soul and the heart. This is the primary reason that the instruction was given to the Prophet salallaho alaihe wasallam in regards to purifying people first, and subsequently teaching Quran and the Sunnah. Reason being, this could be viewed as necessary means towards understanding the Quran and the Sunnah, and most importantly, implementing into our daily lives.
Our goal is to pass on these sciences of our religion, including both the inward and the outward aspect. This is a Sacred Trust that was given to the creation of Allah ta'ala but they refused to accept, but the human being took it. Now he has to inherit it from the previous generations and has the responsibility to pass it on.
The outward sciences can be learnt through various traditional courses. The goal of learning inward sciences is accomplished by connecting to a shaykh who can teach the practical aspects of the Quran and sunnah. When one understands the inner sciences of the self and purifies himself, he attains the sound heart and the moral character that is required of him, as Allah ta'ala states that it is the only thing that will prove beneficial on the day of judgment:
“The Day (of judgment is the one) when neither wealth nor sons will be of any benefit, But only he (will prosper) that brings to Allah a sound heart”
And as the Prophet salallaho alaihe wasallam said;
“I have only been sent to perfect noble character”