This refers to two of the Jews contemporary with the prophet: One of them named ABDULLAH- IBN- SALAM, was a trustworthy and virtuous man. A wealthy Muslim entrusted him with a hoard of gold that amounted to 1200 GHIAS= 840 KG. Abdullah gave him back all his deposite in due time and term.
The second Jew was a vicious traitor whose name was FANÄS; to whom an Arab entrusted one Dinar (a gold coin equal to 66.36 Grains). Fanäs betrayed and denied the trust; when the said verse revealed to this effect.