1 Corinthians 7:37; 1 Corinthians 15:58

37 But he who stands firm in his heart, being under no constraint, but has authority over his own will, and has decided this in his own heart, to keep his own virgin daughter, he will do well.

58 Therefore, my beloved brethren, be steadfast, immovable, always abounding in the work of the Lord , knowing that your toil is not in vain in the Lord .