Amr bin Maymun said: I sat in the gathering of Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) for a year, and I did not hear him narrate from the Messenger of Allah (peace and blessings be upon him). Then one day he said: "The Messenger of Allah (peace and blessings be upon him) said," then his face changed, then he said: "Like this, or a little more than this, or a little less than this."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8583