Al-Kāfi - Volume 1 > Chapter on the quality of knowledge its virtue and the virtue of the scholars
Hadith #2

2ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ عِيسَى عَنْ مُحَمَّدِ بْنِ خَالِدٍ عَنْ أَبِي الْبَخْتَرِيِّ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ السَّلام) قَالَ إِنَّ الْعُلَمَاءَ وَرَثَةُ الانْبِيَاءِ وَذَاكَ أَنَّ الانْبِيَاءَ لَمْ يُورِثُوا دِرْهَماً وَلا دِينَاراً وَإِنَّمَا أَوْرَثُوا أَحَادِيثَ مِنْ أَحَادِيثِهِمْ فَمَنْ أَخَذَ بِشَيْ‏ءٍ مِنْهَا فَقَدْ أَخَذَ حَظّاً وَافِراً فَانْظُرُوا عِلْمَكُمْ هَذَا عَمَّنْ تَأْخُذُونَهُ فَإِنَّ فِينَا أَهْلَ الْبَيْتِ فِي كُلِّ خَلَفٍ عُدُولاً يَنْفُونَ عَنْهُ تَحْرِيفَ الْغَالِينَ وَانْتِحَالَ الْمُبْطِلِينَ وَتَأْوِيلَ الْجَاهِلِينَ.

2. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad ibn ‘Isa from Muhammad ibn Khalid from abu al-Bakhtari from abu ‘Abdallah (a.s.) who has said the following. “The scholars are the heirs of the prophets because the prophets did not leave any Dirham or Dinar, (units of money) as their legacy. What they left was certain pieces of their statements. Those who acquired anything of these pieces of their statements they have certainly gained a large share. You must be very careful, when acquiring such knowledge, to see from what kinds of people you receive them. Among us (the Ahlul Bayt, family of the holy Prophet s.a.) after every one there comes a just person who removes (and exposes) the forgeries of the exaggerators from it (knowledge), the infiltrated materials of the fallacious ones and the interpretations of the ignorant ones.”