Sayyiduna Wathilah bin al-Asqa' (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "The greatest of lies is that a man attributes his lineage to someone other than his father, or tells a lie against the Messenger of Allah (peace and blessings be upon him), or lies about what his eyes have seen."
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18444