Charles Ellicott Commentary John 17:2

"even as thou gavest him authority over all flesh, that to all whom thou hast given him, he should give eternal life." — John 17:2 (ASV)

As you have given him power over all flesh.—Better, According as you gave Him... This is the ground on which the prayer in John 17:1 is based. (John 13:3.) The glory for which He asks is in accordance with the decree which appointed His Messianic work.

“All flesh” represents a Greek translation of a Hebrew phrase. It occurs again in Matthew 24:22; Mark 13:20; Luke 3:6; Acts 2:17; Romans 3:20; 1 Corinthians 1:29; 1 Corinthians 15:39; Galatians 2:16; 1 Peter 1:24. St. John uses it in this place only. Its particular signification is humanity as such, considered in its weakness and imperfection.

That he should give eternal life to as many as you have given him.—Literally, That all whom you gave Him, He may give to them eternal life. (Compare to John 17:6, and Note on John 6:37 and following.) The word “all” is in the Greek a neuter singular, and signifies collectively the whole body of humanity given to Christ. The word for “to them” is masculine and plural, and signifies the individual reception on the part of those to whom eternal life is given. (Compare to Notes on John 6:39-40.)