Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
darimi:647 – Muḥammad b. Yūsuf > Sufyān > Ṭāriq > Ḥakīm b. Jābir

[Machine] Abdullah said, "Indeed, everything has a harm, and the harm of knowledge is forgetfulness."  

الدارمي:٦٤٧ – أَخْبَرَنَا مُحَمَّدُ بْنُ يُوسُفَ عَنْ سُفْيَانَ عَنْ طَارِقٍ عَنْ حَكِيمِ بْنِ جَابِرٍ قَالَ قَالَ

عَبْدُ اللَّهِ «إِنَّ لِكُلِّ شَيْءٍ آفَةً وَآفَةُ الْعِلْمِ النِّسْيَانُ»  

See similar narrations below:

Collected by Dārimī
darimi:646 – Jaʿfar b. ʿAwn > Abū ʿUmays > al-Qāsim

[Machine] "Abdullah, the flaw of speech is forgetfulness."  

الدارمي:٦٤٦ – أَخْبَرَنَا جَعْفَرُ بْنُ عَوْنٍ أَنْبَأَنَا أَبُو عُمَيْسٍ عَنِ الْقَاسِمِ قَالَ قَالَ

عَبْدُ اللَّهِ «آفَةُ الْحَدِيثِ النِّسْيَانُ»