Albert Barnes Commentary 1 Corinthians 3:8

"Now he that planteth and he that watereth are one: but each shall receive his own reward according to his own labor." — 1 Corinthians 3:8 (ASV)

Are one. en eisin. They are not the same person, but they are one in the following respects:

1. They are united in reference to the same work. Though they are engaged in different things—for planting and watering are different kinds of work—yet it is one in regard to the end to be gained. The employments do not at all clash, but tend to the same end. It is not as if one planted, and the other was engaged in pulling up.
2. Their work is one, because one is as necessary as the other. If the grain was not planted, there would be no use in pouring water there; if not watered, there would be no use in planting. The work of one is as needful, therefore, as the other; and the one should not undervalue the labors of the other.
3. They are one in regard to God. They are both engaged in performing one work; God is performing another. There are not three parties or portions of the work, but two. They two perform one part of the work; God alone performs the other. Theirs would be useless without Him; He would not ordinarily perform His, without their performing their part. They could not do His part, even if they wished to—as they cannot make a plant grow; He could perform their part—as He could plant and water without the farmer; but it is not in accordance with His arrangements to do it.

And every man. The argument of the apostle here has reference only to ministers; but it is equally true of all men, that they will receive their proper reward.

Shall receive. In the day of judgment, when God decides the destiny of men. The decisions of that day will be simply determining what every moral agent ought to receive.

His own reward. His fit or proper ton idion reward; that which pertains to him, or which will be a proper expression of the character and value of his labor. The word reward, misyon, properly denotes that which is given by contract for service rendered; an equivalent in value for services or for kindness. (See Barnes on Romans 4:4).

In the Scriptures it denotes pay, wages, recompense given to day-laborers, to soldiers, etc. It is applied often, as here, to the retribution which God will make to men in the day of judgment; and is applied to the favors which He will then bestow on them, or to the punishment which He will inflict as the reward of their deeds.

Instances of the former sense occur in Matthew 5:12, Matthew 6; Luke 6:23, 35; Revelation 11:18; of the latter in 2 Peter 2:13, 15. In regard to the righteous, it does not imply merit, or that they deserve heaven; but it means that God will render to them that which, according to the terms of His new covenant, He has promised, and which will be a fit expression of His acceptance of their services.

It is proper, according to these arrangements, that they should be blessed in heaven. It would not be proper that they should be cast down to hell. Their original and their sole title to eternal life is the grace of God through Jesus Christ; the measure, or amount of the favors bestowed on them there, will be according to the services which they render on earth. A parent may resolve to divide his estate among his sons, and their title to anything may be derived from his mere favor; but he may determine that it shall be divided according to their expressions of attachment, and to their obedience to him.