O disciple, advice is easy – what is difficult is accepting it, for it is bitter in taste to those who pursue vain pleasures, since forbidden things are dear to their hearts. [This is] particularly so for whoever is the student of conventional knowledge, who is occupied with gratifying his ego and with worldly exploits, for he supposes that his knowledge alone will be his salvation and his deliverance is in it, and that he can do without deeds – and this is the conviction of the philosophers. Glory be to God Almighty! This conceited fool does not know that when he acquires knowledge, if he does not act on the strength of it, the evidence against him will become decisive, as the Messenger of God (صلى الله عليه وسلم) said, ‘The man most severely punished on the Day of Resurrection is a scholar whom God did not benefit by his knowledge.’ 
 Ismā‘īl ibn Muḥammad al-Jarrāḥī, Kashf al-khafā’ wa muzīl ’l-ilbās, vol, 1, p. 145, ḥadīth 376; also ‘Alā al-Dīn al-Muttaqī al-Hindī, Kanz al-‘ummāl, vol. 10, p. 187, ḥadīth 28977
[Imām Abū Ḥāmid al-Ghazālī, Letter to a Disciple: Ayyuhā ’l-Walad, translated by Tobias Mayer, Islamic Texts Society, Cambridge, 2005, p. 6]
Allah’s salutations be upon Muhammad (صلى الله عليه وسلم), the Chief of all the Prophets and Apostles, the one bestowed with the distinction of interceding for the sinful, and the one sent as a mercy and blessing to mankind. Allah had chosen him, before the creation of the Pen and the Preserved Tablet, to lead all Prophets and Apostles. And selected him for conveying His message to mankind. He was selected to describe His bounties and boundless treasures that were beyond human comprehension.
Allah (سبحانه وتعالى) endowed him with those branches of knowledge, relating to His Magnificent Self, which were never unfolded to mankind. Allah revealed to him such of His glorious and illustrious attributes, which none knew before; neither a close angel nor an Apostle. His chest was opened and he was empowered with the capability to comprehend all the hidden qualities placed in man – qualities by means of which man can achieve proximity to Allah, and seek guidance in the affairs of this world and the Hereafter.
Allah (سبحانه وتعالى) taught RasulAllah (صلى الله عليه وسلم) the means of correcting the deeds of human beings, which are continually stemming from them with every passing moment. The correction of deeds forms the cornerstone of success in this world and the Hereafter, just as improper deeds result in deprivation and failure in both worlds.
May Allah (سبحانه وتعالى) be pleased with the Sahabah. They acquired knowledge – knowledge which is more numerous than the leaves of trees and the drops of rain – that continually stem from the Prophet (صلى الله عليه وسلم). Then they committed it to their memory and preserved it in the most befitting manner. They accompanied the Prophet (صلى الله عليه وسلم) on journeys and at home, and participated in all his pre-occupations: Da‘wah, Jihād, ‘Ibādāt, Mu‘āmalāt (transactions) and Mu‘āsharāt (social affairs). Then they learned to practice these deeds according to the Sunnah of RasulAllah (صلى الله عليه وسلم) in his presence.
Blessed are the Sahabah, who acquired knowledge and its application directly from RasulAllah (صلى الله عليه وسلم), without any intermediaries. Furthermore, they did not restrict these branches of knowledge to themselves; rather they conveyed this knowledge and wisdom, which was preserved in their hearts and the deeds that they performed, to others. Thus illuminating the Universe with Divine knowledge and spiritual Prophetic deeds. As a result of their endeavours, the whole world became a cradle of learning and scholarship. Men became fountains of light and guidance; and their lives became firmly grounded on ‘Ibādah and Khilāfah.
[Shaykh Muhammad Yusuf Kandhlawi, Preface, اماني الاحبار في شرح معاني الآثار (Amānī al-Aḥbār Fī Sharḥ Ma’ānī al-Āthār)]