Paul was comparing himself to other apostles in 1 Corinthians 15:9-11. There, he said that the grace of God that was with him gave him the strength to work harder than any of them.
In his letter to Titus (Titus 2:9-14), he stated that grace has brought us salvation and is instructing us regarding how to live.
“And now I commit you to God and to the message of His grace, which is able to build you up and to give you an inheritance among all who are sanctified.”
(Acts 20:32 Holman Christian Standard Bible ®©)