The secret of the Lord is with those who fear him. Some read it "the friendship." It signifies familiar fellowship, confidential intimacy, and select fellowship. This is a great secret.
Carnal minds cannot guess what is intended by it, and even believers cannot explain it in words, for it must be felt to be known.
The higher spiritual life is necessarily a path which the eagle's eye has not known, and which the lion's whelp has not traveled; neither natural wisdom nor strength can force a door into this inner chamber.
Saints have the key of Heaven's hieroglyphics they can unriddle celestial enigmas. They are initiated into the fellowship of the skies they have heard words which it is not possible for them to repeat to their fellows.
And he will show them his covenant. Its antiquity, security, righteousness, fullness, graciousness and excellence shall be revealed to their hearts and understandings.
Above all, their own part in it shall be sealed to their souls by the witness of the Holy Spirit. The designs of love which the Lord has to his people in the covenant of grace, he has been pleased to show to believers in the Book of Inspiration, and by his Spirit, he leads us into the mystery, even the hidden mystery of redemption. He who does not know the meaning of this verse, will never learn it from a commentary let him look to the cross, for the secret lies there.
[Charles Spurgeon]

Psalm 25:14 ... The secret of the Lord is with them that fear him; and he will shew them his covenant. ❤