Complete Commentary on the Whole Bible, by Matthew Henry, at sacred-texts.com
Unlawful marriages and fleshly lusts.
Here is a law against all conformity to the corrupt usages of the heathen. Also laws against incest, against brutal lusts, and barbarous idolatries; and the enforcement of these laws from the ruin of the Canaanites. God here gives moral precepts. Close and constant adherence to God's ordinances is the most effectual preservative from gross sin. The grace of God only will secure us; that grace is to be expected only in the use of the means of grace. Nor does He ever leave any to their hearts' lusts, till they have left him and his services.