1 Corinthians 15:10
But by God's unmerited favor I have become what I am, and His unmerited favor shown to me was not bestowed for nothing, for I have toiled more extensively than any of them, and yet it was not I but God's unmerited favor working with me.
1 Corinthians 15:58
So, my dear brothers, continue to be firm, incapable of being moved, always letting the cup run over in the work of the Lord, because you know that your labor in the service of the Lord is never thrown away.
Galatians 6:9
Let us stop getting tired of doing good, for at the proper time we shall reap if we do not give up.
Colossians 1:29
For this I am toiling and struggling by His active energy which is mightily working in me.