Merits of the Helpers in Madinah (Ansaar)

Bukhari :: Book 5 :: Volume 58 :: Hadith 159

Narrated Abu Burda:

When I came to Medina. I met Abdullah bin Salam. He said, "Will you come to me so that I may serve you with Sawiq (i.e. powdered barley) and dates, and let you enter a (blessed) house that in which the Prophet entered?" Then he added, "You are In a country where the practice of Riba (i.e. usury) is prevalent; so if somebody owe you something and he sends you a present of a load of chopped straw or a load of barley or a load of provender then do not take it, as it is Riba."