1 Corinthians 15:58 in the King James Version
Therefore, my beloved brethren, be ye stedfast, unmoveable, always abounding in the work of the Lord, forasmuch as ye know that your labour is not in vain in the Lord.
Context
57 But thanks be to God, who gives us the victory through our Lord Jesus Christ.
58 Therefore, my beloved brothers, be steadfast, immovable, always abounding in the Lord’s work, because you know that your labor is not in vain in the Lord.