John 15:25

But this cometh to pass

(αλλ'). Ellipsis in the Greek (no verb), as in John 9:3; John 13:18.In their law

(εν τω νομω αυτων). Cf. John 8:17; John 10:34 for this standpoint. "Law" (νομος) here is for the whole of Scripture as in John 12:34. The allusion is to Psalms 69:4 (or Psalms 35:19). The hatred of the Jews toward Jesus the promised Messiah (John 1:11) is "part of the mysterious purpose of God" (Bernard) as shown by ινα πληρωθη (first aorist passive subjunctive of πληροω, to fulfil).Without a cause

(δωρεαν). Adverbial accusative of δωρεα from διδωμ, gratuitously, then unnecessarily or gratis (in two Koine tablets, Nageli) as here and Galatians 2:21.