THE SHEKEL

The shekel, Israel's unit of currency, (valued at $0.25 in September 1998), was known as early as the second millennium BCE as a unit of weight for means of payment in gold and silver. It is recorded in the Bible that Abraham negotiated the purchase of a field "and the cave that was therein," at Machpela (near Hebron), saying: "I will give thee money for the field; take it of me, and I will bury my dead there." Ephron, the landowner, replied: "The land is worth four hundred shekels of silver...and Abraham weighed to Ephron... four hundred shekels of silver, current money with the merchant"
(Genesis 23:13, 15-17).

Source
Ministry of Finance
 http://www.mfa.gov.il/mfa/go.asp?MFAH00m50