Thou hast forgiven the iniquity of thy people; thou hast covered all their sin. God's remission of punishment, and restoration of his people to favour, was a full indication that he had "forgiven their iniquity" and "covered their sins."
This was so vast a boon, that a pause for devout acknowledgment and silent adoration seemed fitting. Hence the "selah," which is at the end of the second verse, not of the first, as Hengstenberg states.