Sunan Ibn Majah, Hadith 224 ⓘ
It was narrated from Anas bin Malik that the Messenger of Allah said: "Seeking knowledge is a duty upon every Muslim, and he who imparts knowledge to those who do not deserve it, is like one who puts a necklace of jewels, pearls and gold around the neck of swines."
حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا حَفْصُ بْنُ سُلَيْمَانَ، حَدَّثَنَا كَثِيرُ بْنُ شِنْظِيرٍ، عَنْ مُحَمَّدِ بْنِ سِيرِينَ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " طَلَبُ الْعِلْمِ فَرِيضَةٌ عَلَى كُلِّ مُسْلِمٍ وَوَاضِعُ الْعِلْمِ عِنْدَ غَيْرِ أَهْلِهِ كَمُقَلِّدِ الْخَنَازِيرِ الْجَوْهَرَ وَاللُّؤْلُؤَ وَالذَّهَبَ " .
also referenced under: Book 1, Hadith 229 (In-Book) & Volume 1, Book 1, Hadith 224 (DarusSalam)