The Lord Jesus never commanded His chosen disciples to travel throughout the whole world to preach, because if they did, they would need money and would have to ask people for financial support.Jesus was talking to the twelve, who would eventually become his apostles. Their works will be greater in the sense that they will reach more people with the gospel. They will travel around the known world. Many of them will contribute to the New Testament. We owe a lot to their works.
The Lord Jesus did not want that. Instead, He obeyed God's will without asking people for money.
Therefore, traveling around the whole world to preach cannot be what the Lord meant by "greater works." Rather, the Lord was referring to the degree or magnitude of what His disciples would accomplish, which would be greater than what He Himself did.
