There is not a Bible verse that states "Only what you do for Christ will last." This idea is taken from a verse found in Corinthians.
The verse from 2 Corinthians 5:9-10 states, "So we make it our goal to please him, whether we are at home in the body or away from it. For we must all appear before the judgment seat of Christ, so that each of us may receive what is due us for the things done while in the body, whether good or bad." The message behind this verse is that believers in Christ should focus on pleasing the Lord, realizing that there is no eternal value in the things of the world.