John Gill Commentary Psalms 57:10

"For thy lovingkindness is great unto the heavens, And thy truth unto the skies." — Psalms 57:10 (ASV)

For your mercy [is] great unto the heavens
Which denotes the exceeding greatness and largeness of it; as it is in the heart of God, who is plenteous in mercy; as it is expressed in the covenant of grace, where are stores of it; as it is shown forth in the choice of persons to eternal life; in the mission of Christ into this world to die for them; in the regeneration of them, the pardon of their sins, and eternal life: and this mercy is not only extended to persons in the several parts of the earth, but is as high as the heaven above it, (Psalms 103:11) ;

and your truth unto the clouds ;
the faithfulness of God in performing his purposes and his promises; or the Gospel, and the doctrines of it, which contain the deep things of God; unless Christ himself should be meant, who is the truth which sprung out of the earth, (Psalms 85:11) ; is now ascended unto heaven, and is higher than the heavens; and whose exaltation and glory may be designed in (Psalms 57:11) .