Everyone twenty years of age or older who crosses over must give this offering to the LORD.
Some observe that the repetition of those words, The Lord spoke unto Moses, here and afterwards (Exo 30:17, Exo 30:22, Exo 30:34), intimates that God did not deliver these precepts to Moses in the mount, in a continued discourse, but with many intermissions, giving him time either to write what was said to him or at least to charge his memory with it.
Commenting on Exodus 30:11-16
Every one that passeth among them that are numbered, from twenty years old and above,.... Even Levites, Israelites, proselytes, and servants freed, but not women, bond servants, or children (x): shall give an offering to the Lord; the half shekel before mentioned. (x) Misn. Shekalim, c. 1. sect. 1, 3.
Exo 30:12-15 “When thou takest the sum of the children of Israel according to them that are numbered, they shall give every one an expiation for his soul to the Lord at their numbering, that a plague may not strike them (happen to them) at their numbering.” פּקד, lit., adspexit, then inspexit explorandi causa, hence to review, or number an army or a nation, for...
Commenting on Exodus 30:12-15