What does the Bible say about the Holy Spirit as the Earnest of our inheritance?

In Ephesians 1:13-14, it is stated that after believers have believed, they were sealed with the Holy Spirit of promise, which functions as the Earnest of their inheritance until the redemption of those who are God's own possession. This notion of the Holy Spirit being the Earnest signifies that He is a pledge or guarantee of the glorious inheritance that awaits believers—a spiritual assurance of eternal life purchased by Christ's sacrifice. The Spirit's presence in the life of a believer serves as a confirmation of the ongoing covenant relationship between God and His people, highlighting the gracious nature of God's promises.