Jamieson, Fausset and Brown on Leviticus 18:5

5. Ye shall therefore keep my statutes, and my judgments: which if a man do, he shall live in them--A special blessing was promised to the Israelites on condition of their obedience to the divine law; and this promise was remarkably verified at particular eras of their history, when pure and undefiled religion prevailed among them, in the public prosperity and domestic happiness enjoyed by them as a people. Obedience to the divine law always, indeed, ensures temporal advantages; and this, doubtless, was the primary meaning of the words, "which if a man do, he shall live in them." But that they had a higher reference to spiritual life is evident from the application made of them by our Lord (Lu 10:28) and the apostle (Ro 10:2).