Leviticus 27:5 (KJV)

And the LORD spake unto Moses, saying,

Speak unto the children of Israel, and say unto them, When a man shall make a singular vow, the persons shall be for the LORD by thy estimation.

And thy estimation shall be of the male from twenty years old even unto sixty years old, even thy estimation shall be fifty shekels of silver, after the shekel of the sanctuary.

And if it be a female, then thy estimation shall be thirty shekels.

And if it be from a month old even unto five years old, then thy estimation shall be of the male five shekels of silver, and for the female thy estimation shall be three shekels of silver.

And if it be from sixty years old and above; if it be a male, then thy estimation shall be fifteen shekels, and for the female ten shekels.

But if he be poorer than thy estimation, then he shall present himself before the priest, and the priest shall value him; according to his ability that vowed shall the priest value him.

And if it be a beast, whereof men bring an offering unto the LORD, all that any man giveth of such unto the LORD shall be holy.

He shall not alter it, nor change it, a good for a bad, or a bad for a good: and if he shall at all change beast for beast, then it and the exchange thereof shall be holy.