Mujahid narrates that a man came to Sayyiduna Ibn Umar (may Allah be pleased with them both), and he asked him: How are you and Abu Unays - meaning al-Dahhak bin Qays? He said: As for us and him, when we meet him we say to him what he likes, and when we turn our backs on him we say something else. Sayyiduna Ibn Umar (may Allah be pleased with them both) said: "This is what we used to count as hypocrisy while we were with the Messenger of Allah (peace and blessings be upon him)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13432