Commentaire sur Le Lévitique 26:32

והשמתי אני את הארץ AND I WILL BRING THE LAND INTO DESOLATION [AND YOUR ENEMIES WHO ABIDE IN IT SHALL BE DESOLATE UPON IT] — This was a kindly measure for Israel that the enemies would find no satisfaction in their (the Israelites') land and so it would become desolate of its inhabitants (of the enemies also, and Israel might again easily take possession of it) (Sifra, Bechukotai, Chapter 6 5).

והשמותי אני את הארץ, "And I will make the land desolate, etc." The reason the Torah uses the word אני although it is implied in the word והשמותי is to identify the Attribute of G'd causing this desolation. It is the attribute of mercy. Torat Kohanim explains that the desolation of the land is intended to deny our enemies the pleasure of what had been our land before they conquered it.

ושממו עליה איביכם, when they come there with the intention to settle in them. (compare Tzefaniah 2,15 כל עובר עליה ישרוק, יניע ידו, “everyone who comes by her hisses and gestures with his hand (in disgust).”