John Gills Exposition of the Bible Commentary - Leviticus 27:28
Notwithstanding, no devoted thing that a man shall devote unto the Lord ,.... This is a different vow from the former, expressed by "sanctifying"; for though "sanctifying" and "devoting" were both vows, yet the latter had an execration or curse added to it, by which a man imprecated a curse upon himself, if that itself, which he devoted, was put to any other use than that for which he devoted it; wherefore this sort of vow was absolute and irrevocable, and what was vowed was unalienable, and... read more
Matthew Henry's Complete Commentary - Leviticus 27:26-34
Here is, I. A caution given that no man should make such a jest of sanctifying things to the Lord as to sanctify any firstling to him, for that was his already by the law, Lev. 27:26. Though the matter of a general vow be that which we were before obliged to, as of our sacramental covenant, yet a singular vow should be of that which we were not, in such circumstances and proportions, antecedently bound to. The law concerning the firstlings of unclean beasts (Lev. 27:27) is the same with that... read more