Exodus 30:13

30:13 Everyone who crosses over to those who are numbered is to pay this: a half shekel according to the shekel of the sanctuary (a shekel weighs twenty gerahs). The half shekel is to be an offering to the Lord.

Exodus 30:15

30:15 The rich are not to increase it, and the poor are not to pay less than the half shekel when giving the offering of the Lord, to make atonement for your lives.

Exodus 38:26

38:26 one beka per person, that is, a half shekel, according to the sanctuary shekel, for everyone who crossed over to those numbered, from twenty years old or older, 603,550 in all.