Adam Clarke on 1 Corinthians 3:8

He that planteth and he that watereth are one - Both Paul and Apollos have received the same doctrine, preach the same doctrine, and labor to promote the glory of God in the salvation of your souls. Why should you be divided with respect to Paul and Apollos, while these apostles are intimately One in spirit, design, and operation?

According to his own labor - God does not reward his servants according to the success of their labor, because that depends on himself; but he rewards them according to the quantum of faithful labor which they bestow on his work. In this sense none can say, I have labored in vain, and spent my strength for nought.