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 Allah 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 Allah ﷺ said, ‘The man most severely punished on the Day of Resurrection is a scholar whom Allah did not benefit by his knowledge.’ [1]

[1] ‘Ala al-Dīn al-Muttaqi al-Hindi, Kanz al-‘Ummāl, vol. 10, p. 187, ḥadith #28977

[Cf. Imam Abu Hamid al-Ghazali, Letter to a Disciple: Ayyuhā ’l-Walad, translated by Tobias Mayer, Islamic Texts Society, Cambridge, 2005, p. 6]