Verse 7 is the conclusion to the previous statement that New World prophets might command nature. However, it is also the transition to the next theme, which is the power of Jehovah. It is Jehovah who has dominion over the earth; the prophets, in their weakness, may call upon Jehovah to exercise his power according to their word and faith. This is a great gift to humankind. God is far above our understanding, and yet will condescend to work with us, and for us.
Jacob notes the extent of this power upon which prophets might call by noting that all of creation came by the power of his word. Therefore, Jehovah can command, and even the trees, and mountains, and sea will obey. Lest anyone think that the prophets who Jacob said could do these things in verse 6 could do them of themselves, Jacob makes it clear that it is Jehovah’s power that accomplishes these great and marvelous works.