A.T. Robertson Commentary John 6:27

"Work not for the food which perisheth, but for the food which abideth unto eternal life, which the Son of man shall give unto you: for him the Father, even God, hath sealed." — John 6:27 (ASV)

Work not for (μη εργαζεσθε). Prohibition with μη and present middle imperative of εργαζομα, old verb from εργον, work.

The meat (την βρωσιν). The act of eating (Romans 14:17), corrosion (Matthew 6:19), the thing eaten as here (2 Corinthians 9:10). See on Joh 4:32.

Which perisheth (την απολλυμενην). Present middle participle of απολλυμ. They were already hungry again.

Unto eternal life (εις ζωην αιωνιον). Mystical metaphor quite beyond this crowd hungry only for more loaves and fishes. Bernard thinks that John has here put together various sayings of Christ to make one discourse, a gratuitous interpretation.

Will give (δωσε). Future active indicative of διδωμ. The outcome is still future and will be decided by their attitude towards the Son of man (verse 51).

For him the Father, even God, hath sealed (τουτον γαρ ο πατηρ εσφραγισεν ο θεος). Literally, "For this one the Father sealed, God." First aorist active indicative of σφραγιζω, to seal. See elsewhere in Joh 3:33 (attestation by man). Sealing by God is rare in N.T. (2 Corinthians 1:22; Ephesians 1:13; Ephesians 4:30). It is not clear to what item, if any single one, John refers when the Father set his seal of approval on the Son. It was done at his baptism when the Holy Spirit came upon him and the Father spoke to him. Cf. 5:37.