Charles H. Spurgeon on Psalms 98:2

The LORD hath made known, etc. The word uydx denotes not only a publication and promulgation, but also a clear and certain demonstration which produces conviction and causes the matter to be laid up in the mind and memory and preserved: for the proper signification of the root ydy is to lay up what is to be preserved. The word hlg is added, which properly means to uncover, to be uncovered, hence he revealed or uncovered, that it might be both naked and clear, for the purpose of more fully illustrating the character of the manifestation of the Gospel, opposed to what is obscure, involved in shadows and types, and veiled in legal ceremonies. Of which the apostle treats expressly in 2Co 3:7-18. Lastly, when it is added, that in the sight of the nations this uncovering is done, it signifies that this salvation pertains to them also, that it comes to them without distinction, since the Gospel is nakedly and clearly announced. From which it also clearly appears, that the matter reason of the new song are found in such a singular event, since God who formerly permitted the nations to walk in their own ways, now under Messiah calls all without distraction to salvation through faith and newness of life. Venema.