Leviticus 27:3

And thy estimation shall be
The estimation of the man himself that vowed, or of the priest for him, was not left to be made by either of them at their pleasure, but was to be made according to the following rules, in proportion to the age a person was of to be estimated:

of the male from twenty years old even unto sixty years old:
the account begins with these, because men of an age from the one to the other are fittest for labour, and therefore to be set at the highest price, as they are in the next clause:

even that estimation shall be fifty shekels of silver, after the
shekel of the sanctuary;
a shekel was about half a crown of our money, or somewhat less, so that fifty of these amounted to about six pounds: these shekels were to be of the full weight, according to the standard that was kept in the sanctuary, and were the highest price that was set upon any; and this was paid equally by all of the same age, whether rich or poor: hence it is said,

``in estimations there is nothing less than one shekel, nor more than fifty ^F14.''