John Gill's Bible Commentary Ver. 5. And if [it be] from five years old, even unto to twenty years old , etc.] Not that one of five years old is supposed to vow or to make an estimation, but one grown up, that says, the estimation of this little one, who is five years of age, be upon me; and such an one was bound to pay the value of him, which is as follows: then thy estimation shall be of the male twenty shekels, and for the female ten shekels ; which were for the one above two pounds, and for the other more than one pound; these were valued at a less price than the former, partly because, generally speaking, there are more die between the age of five and the age of twenty years than between twenty and sixty; and partly because within that time they are not capable of so much work and service as in the latter; and it may be observed, that the females of this age are not valued in proportion to the females of the other; the estimation of these being just half that of the males, whereas that of the other is more than half; the reason is, that women above twenty years of age, their service bears, a better proportion to that of men, than that of young women to young men under twenty.
Matthew Henry Commentary
Verses 1-13 - Zeal for the service of God disposed the Israelites, on some occasions to dedicate themselves or their children to the service of the Lord, in his house for life. Some persons who thus dedicated themselves might be employed as assistants; in general they were to be redeemed for value. It is good to be zealously affected and liberally disposed for the Lord's service; but the matter should be well weighed, and prudenc should direct as to what we do; else rash vows and hesitation in doin them will dishonour God, and trouble our own minds.
Original Hebrew ואם518 מבן1121 חמשׁ2568 שׁנים8141 ועד5704 בן1121 עשׂרים6242 שׁנה8141 והיה1961 ערכך6187 הזכר2145 עשׂרים6242 שׁקלים8255 ולנקבה5347 עשׂרת6235 שׁקלים׃8255