Deuteronomy 28:9

9.The Lord shall establish thee a holy people unto himself. This refers indeed to earthly blessings, as if Moses said, that by them would be manifested God’s love towards His chosen people; still it rises higher, so that the Israelites, led on by degrees, should learn to embrace God alone, and to trust in Him according to the covenant which He had made with Abraham, “I am thy exceeding great reward.” (Genesis 15:1.) For the children of Abraham were set apart and chosen to be a holy people, not only in order that, being well fed, and with a full belly, they should aspire to nothing but earthly things, but that they might be confidently assured that they would be blessed in death as well as life. Although their adoption was gratuitous, still, inasmuch as they were called unto purity, it is not without reason that God promises that what He had spoken should be sure, if by keeping the Law the Israelites themselves should continue in the covenant; as much as to say, that their sanctification (215) should be firm and perpetual if they walked in the commandments of the Law. When He adds that it should be manifest “to (216) all people of the earth that the name of God was called upon them,” it is equivalent to saying, that it should be known that they were under God’s defense and patronage, and that thus they should always be safe and secure in His protection.