Abu Burdah narrates: I came to Madinah and sat with Sayyiduna Abdullah bin Salam (may Allah be pleased with him), and he said: "Will you not come home, pray in a mosque in which the Messenger of Allah (peace and blessings be upon him) prayed, and drink from a cup from which the Messenger of Allah (peace and blessings be upon him) drank?" So I went with him, and he said to me: "You are in a land where showing off (riya') is widespread, and part of showing off is that a man greets (someone) with salam, then is given a gift, and he accepts it."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13989