1 Corinthians 4:17

4:17 For this reason, I have sent Timothy to you, who is my dear and faithful son in the Lord. He will remind you of my ways in Christ, as I teach them everywhere in every church.

1 Corinthians 15:58

15:58 So then, dear brothers and sisters, be firm. Do not be moved! Always be outstanding in the work of the Lord, knowing that your labor is not in vain in the Lord.