They stand fast forever and ever. This is exegetical of the "sure" in Psalms 111:7. In the sense in which they were given—the spiritual sense underlying them—not one jot or tittle of God's commandments ever passes away (Matthew 5:18).
And are done in truth and uprightness; rather, being done. It is the intrinsic truth and equity of the commandments that render them ever lasting and unchangeable (see Cudworth on 'Immutable Morality').