It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "Isa bin Maryam (peace be upon him) said: Matters are of three kinds: a matter whose rightness is clear to you, so follow it; a matter whose error is clear to you, so avoid it; and a matter about which there is disagreement, so refer it to the one who knows it."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10728