In his hand are the deep places of the earth - The greatest deeps are fathomed by him.

The strength of the hills is his also - And to him the greatest heights are accessible,

in

Psalm 21:2 You have given him his heart's desire, and have not withheld the request of his lips. Selah.

Job 11:10 If he cut off, and shut up, or gather together, then who can hinder him?

his. Heb. whose
deep

Psalm 135:6 Whatever the LORD pleased, that did he in heaven, and in earth, in the seas, and all deep places.

the strength of the hills is his also. or, heights of the hills are his

Psalm 65:6 Which by his strength sets fast the mountains; being girded with power:

Psalm 97:5 The hills melted like wax at the presence of the LORD, at the presence of the Lord of the whole earth.

Job 9:5 Which removes the mountains, and they know not: which overturns them in his anger.

Micah 1:4 And the mountains shall be molten under him, and the valleys shall be cleft, as wax before the fire...

Nahum 1:5 The mountains quake at him, and the hills melt, and the earth is burned at his presence, yes, the world, and all that dwell therein.

Habakkuk 3:6,10 He stood, and measured the earth: he beheld, and drove asunder the nations; and the everlasting mountains were scattered...

Covenanting a Duty.
The exercise of Covenanting with God is enjoined by Him as the Supreme Moral Governor of all. That his Covenant should be acceded to, by men in every age and condition, is ordained as a law, sanctioned by his high authority,--recorded in his law of perpetual moral obligation on men, as a statute decreed by him, and in virtue of his underived sovereignty, promulgated by his command. "He hath commanded his covenant for ever."[171] The exercise is inculcated according to the will of God, as King and …
John Cunningham—The Ordinance of Covenanting

Psalms
The piety of the Old Testament Church is reflected with more clearness and variety in the Psalter than in any other book of the Old Testament. It constitutes the response of the Church to the divine demands of prophecy, and, in a less degree, of law; or, rather, it expresses those emotions and aspirations of the universal heart which lie deeper than any formal demand. It is the speech of the soul face to face with God. Its words are as simple and unaffected as human words can be, for it is the genius …
John Edgar McFadyen—Introduction to the Old Testament