The Apostle Paul
Ephesians 1:14BSB·traditional attribution

who is the pledge of our inheritance until the redemption of those who are God’s possession, to the praise of His glory.

John Calvin Reformed @genevareformer

14. Which is the earnest “The original word ἀρ᾿ῥαβών, seems properly to denote the first part of the price that is paid in any contract, as an earnest and security of the remainder, and which, therefore, is not taken back, but kept till the residue is paid to complete the whole sum.

Matthew Henry Presbyterian @wholebiblehenry

He begins with thanksgivings and praise, and enlarges with a great deal of fluency and copiousness of affection upon the exceedingly great and precious benefits which we enjoy by Jesus Christ. For the great privileges of our religion are very aptly recounted and enlarged upon in our praises to God. I.

Commenting on Ephesians 1:3-14

John Gill Reformed Baptist @doctorgill

Which is the earnest of our inheritance,.... The incorruptible and never fading one in heaven, or the heavenly kingdom; this is the Father's gift, his bequest, and belongs only to children; it comes to them through the death of the testator, Christ, and is for ever; and of this the Spirit of God is the pledge and earnest: an earnest, is what confirms an agreement...