A.T. Robertson Commentary John 18:9

"that the word might be fulfilled which he spake, Of those whom thou hast given me I lost not one." — John 18:9 (ASV)

That might be fulfilled (ινα πληρωθη). The regular formula (17:12) for Scripture, here applied to the prophecy of Jesus (17:12) as in verse 32. John treats the saying of Jesus as on a par with the O.T.