What does the Bible say about God's promises and their assurance?

The assurance of God's promises stems from the covenant established through Jesus, which is founded on better promises than those of the old covenant. Hebrews 7:22 reveals Christ as the Surety of a better testament, affirming that His work is complete and sufficient for salvation. The promises God makes are grounded in Christ's righteousness, ensuring that they cannot fail or be revoked. This profound assurance is what allows believers to rest in the certainty of their salvation and the fulfilling of God's covenantal promises to them, as outlined in Hebrews 8:12, where God promises to remember their sins no more.