Jamieson, Fausset and Brown on Leviticus 26:46

46. These are the statutes and judgments and laws--It has been thought by some that the last chapter was originally placed after the twenty-fifth [Adam Clarke], while others consider that the next chapter was added as an appendix, in consequence of many people being influenced by the promises and threats of the preceding one, to resolve that they would dedicate themselves and their possessions to the service of God [Calmet].