Adam Clarke on Psalms 97:12

Rejoice in the Lord, ye righteous - It is your privilege to be happy. Exult in him through whom ye have received the atonement. Rejoice; but let it be in the Lord. All other joy is the mirth of fools, which is as the crackling of thorns under a pot - it is a luminous blaze for a moment, and leaves nothing but smoke and ashes behind.

At the remembrance of his holiness - But why should you give thanks at the remembrance that God is holy? Because he has said, Be ye holy; for I am holy: and in holiness alone true happiness is to be found. As he, therefore, who hath called you is holy; so be ye holy in all manner of conversation. False Christians hate the doctrine of Christian holiness; they are willing to be holy in another, but not holy in themselves. There is too much cross-bearing and self-denial in the doctrine of holiness for them. A perfect heart they neither expect nor wish.

The analysis considers the whole Psalm as relating to Jesus Christ and the last judgment: so it was understood by several of the ancient fathers. The reader may take it in either sense.