William Burkitt on 2 Corinthians 3:4

Observe here, How the apostle encourages himself, from the experience he had of the present success of his ministry, to hope for the favour of farther and future success: Such trust or confidence have we, through the grace of Christ, of the constant efficacy of our ministry, that he will still own and honour it, succeed and bless it.

When God has rendered our labours acceptable and successful amongst a people, either for conversion or edification, it should encourge us to trust in God for the efficacious assistance of our ministry, and render us yet more successful amongst them, and a greater blessing to them.