Psalms 99:2

The Lord is great in Zion - It is among his own worshippers that he has manifested his power and glory in an especial manner. There he is known, and there he is worthily magnified.

The Lord is great in Zion - Compare Psalm 95:3. The meaning here is, not that God is "absolutely" great - which is indeed true - but that there is a sense in which he has shown himself great "in Zion;" that is, in his manifestations toward his own people. He has evinced power in their behalf; he has interposed for them in times of danger; he has so discomfited their enemies as to show that he is a great God - a God worthy to be adored.

And he is high above all the people - Above all the nations. He has them under his control. He rules over all. The God who rules in Zion also rules all the nations of the earth; and his people, therefore, have special occasion to praise him.