How does the story of Ishmael and Isaac relate to salvation?

In Galatians 4, Paul uses the story of Ishmael and Isaac to depict the two covenants: the covenant of works (represented by Ishmael) and the covenant of grace (illustrated through Isaac). Ishmael, born of Hagar, symbolizes human effort and the law, which leads to slavery and death, while Isaac, born of Sarah, signifies God's promise and grace, leading to freedom and life. This dichotomy highlights that salvation cannot incorporate our works but must rely solely on the grace of God. Trusting in works leads one away from true salvation, emphasizing the essential need for believers to rest in the sufficiency of Christ's finished work alone, corroborated by Romans 4:4-5, which states, 'Now to the one who works, his wage is not counted as a gift but as his due. And to the one who does not work but believes in him who justifies the ungodly, his faith is counted as righteousness.'