Exodus 30:11-13

11And Jehovah spoke to Moses, saying,

12When thou shalt take the sum of the children of Israel according to those of them that are numbered, then shall they give every man a ransom for his soul to Jehovah on their being numbered, that there be no plague among them on their being numbered.

13This shall they give — every one that passeth among them that are numbered — half a shekel after the shekel of the sanctuary, — twenty gerahs the shekel; a half shekel shall be the heave-offering for Jehovah.