Albert Barnes Commentary Psalms 111:8

"They are established for ever and ever; They are done in truth and uprightness." — Psalms 111:8 (ASV)

They stand fast forever and ever — Margin, “established.” The Hebrew word means “sustained, supported.” They will not fail or fall. Whatever else may be shaken, his law, his word, and the principles of his administration, will not fail.

See the notes at Matthew 5:18. Compare to Luke 16:17 and Matthew 24:35. The great principles of truth and righteousness will stand, and whatever is founded on those principles will endure forever.

And are done in truth and uprightness — Are based on truth, or on a just view of things; they are done in such a way that truth will be maintained and promoted. The word “uprightness” here means that all this is done on the principles of equity—of what “ought” to be done, or what is “best” to be done. Compare to Psalms 19:9.