Acts 18:10

for I am with thee The pronoun is expressed emphatically in the Greek, and no man shall set on thee to hurt[harm] thee. There will be assailants. Christ does not promise him freedom from attack. But the enemy shall not be able to do him violence. And this appearance of Christ would give the Apostle the confidence of the prophet of old (2 Kings 6:16), "They that be with us are more than they that be with them."

for I have much people in this city How important and extensive was the Christian community at Corinth we may gather from the Epistles which St Paul wrote afterwards to the Church there. And as the city was one of the great centres of commercial activity at this period, we can see how important it was (humanly speaking) for the Church to make good its footing there from the first. The Lord mercifully by this vision gave his servant assurance that his words should be largely blessed, and rising up thus comforted, he was ready for any task.