John Gill Commentary Ezekiel 31:7

"Thus was it fair in its greatness, in the length of its branches; for its root was by many waters." — Ezekiel 31:7 (ASV)

Thus was he fair in his greatness Amiable, lovely, delightful to look upon in the greatness of his majesty, in his royal glory and dignity:

in the length of his branches in the extent of his empire, and the provinces of it:

for his root was by great waters his kingdom was well established, firmly rooted among a multitude of people; from whom he had a large revenue to support his throne and government, and the dignity of it; by tribute, taxes, customs, and presents; and through the large trade and traffic of his subjects in different parts, from which he received great profit and advantage.

The Targum is, "and he became victorious by his auxiliaries, by the multitude of his mighty ones, so that his terror was upon many people."