It is narrated from Sayyiduna Salman al-Farisi (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever deliberately lies about me, let him take up his abode in Hell; and whoever rejects a hadith that reaches him from me, let him take up his abode in Hell; and whoever rejects a hadith that reaches him from me, I will be his opponent on the Day of Resurrection. When a hadith reaches you from me that you do not recognise, say: Allah knows best."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6138