Ash-Shama'il Al-Muhammadiyah, Book 56, Hadith 415 (In-Book) ⓘ
Ibn Seereen says: "The knowledge of hadith (in the same manner all other religious subjects) are included in the deen. Therefore before acquiring knowledge, be aware from whom knowledge is acquired".
حدثنا محمد بن علي، حدثنا النضر بن عون، عن ابن سيرين قال: هذا الحديث دين، فانظروا عمن تأخذون دينكم..
also referenced under: Book 55, Hadith 397 (English)