From The Dangers of Having Knowledge Without Acting Upon It…
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Al-Imām Al-Ḥāfiẓ Ibn Rajab Al-Ḥanbalī (رحمه الله) Mentioned:
That is why the most severely tormented person in the Ākhirah (Hereafter) was a scholar who Allāh did not benefit him with his knowledge, and he is the most grieving of the people on the Day of Resurrection, as he had a tool with him (knowledge) with which he could have reached the highest of ranks, and the loftiest of stations, and he only used it to reach the lowest and most despicable of things, so he is like someone who had precious jewels of value and sold them for dung or something filthy.
Majmūʿ Rasā’il Ibn Rajab (1/ 79)
Translated by AMMAN CIRCLE Editorial