Adam Clarke on Ephesians 2:4

But God, who is rich in mercy - As they were corrupt in their nature, and sinful in their practice, they could possess no merit, nor have any claim upon God; and it required much mercy to remove so much misery, and to pardon such transgressions.

His great love - God's infinite love is the groundwork of our salvation; in reference to us that love assumes the form of mercy, and that mercy provides the Savior, the Lord Jesus Christ. And therefore the apostle adds, Eph 2:5 : By grace ye are saved - it is by God's free mercy in Christ that ye are brought into this state of salvation. See on Eph 2:8 (note).