Beginning with this verse and continuing through verse 30, the Greek text has a play on the verb “to work (for something)” and the noun “work.” In this verse the meaning of the verb work for is “to strive after.”

Food that spoils is translated in Jerusalem Bible as “food that cannot last” and in New English Bible as “this perishable food.” In Greek spoils is actually a participle made from the same stem as the verb used in verse 12 (see comments there on let us not waste a bit).

There is a problem in translating Do not work for food that spoils, since the negative is attached to work rather than to food. It is not an admonition “not to strive” but “to strive not for food that spoils.” In some languages it is necessary to place the negative directly before “for the food that spoils.” Thus it may be more satisfactory to introduce the positive statement first, for example, “Strive to obtain the food that lasts for eternal life and not for the food that spoils.”

Food that lasts for eternal life is translated in Jerusalem Bible “food that endures to eternal life” (see also Revised Standard Version). The idea is that this food lasts because it gives eternal life (see verses 33,50,54,58). Moffatt translates “that lasting food which means eternal life” and New English Bible “food that lasts, the food of eternal life.” (On the meaning of eternal life see comments at 1.4 and 3.15.) It is important to indicate that it is not the food that lasts forever, that is, “it is the food that causes people to live without end.” Only in this sense is the food itself imperishable.

The Greek of this verse is one sentence, and this food is actually a relative pronoun (“which”).

For the Son of Man see 1.51. As in many other instances where this phrase occurs, it may be necessary to introduce a first person pronoun, for example, “I, the Son of Man, will give you this food.”

God, the Father, has put his mark of approval on him is more literally “it is on him that God the Father has set his seal” (New American Bible). In 3.33 the verb “to seal” is used with the believer as the subject and is rendered proves by this (see comments there). In the present passage God, the Father is the subject of the verb. A few commentators equate “the seal of God” with “the likeness of God” (see Col 1.15), which Christ possessed before time began. However, the verb tense more naturally suggests a point in time, such as the coming of Jesus into the world or the descent of the Spirit on Jesus. Other commentators take this sealing to mean either that God has validated the authority of Jesus (New English Bible “upon whom God the Father has set the seal of his authority”) or that God has put his mark of approval on the Son, thus validating his work (Moffatt “has certified him”). Good News Translation follows this last interpretation.

Elsewhere in the New Testament the idea of a “sealing” by God occurs only in 2 Corinthians 1.22; Ephesians 1.13; 4.30. In each of these passages God is spoken of as “sealing” the believer. Good News Translation takes this term to mean that God has placed his mark of ownership on the believer. In the case of the Son of Man, God’s action has a different significance.

The expression God … has put his mark of approval on him is likely to be understood only in too literal a sense if it is translated word for word, that is, “a mark which shows he approves of him.” It may suggest that in some way God had branded Jesus or had provided him with some physical blemish or mark to show his approval. Accordingly, it may be better to drop this figure and translate the essential meaning, for example, “because God the Father has shown that he approves of him” or “… has said, ‘I approve of him.’ ” If the first person singular pronoun has been introduced above in connection with the Son of Man title (“I, the Son of Man”), then a first person singular pronoun should replace the third person singular pronoun here (him). The translation would then read “because God my Father has shown that he approves of me.”

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .