Charles Ellicott Commentary John 15:25

"But [this cometh to pass], that the word may be fulfilled that is written in their law, They hated me without a cause." — John 15:25 (ASV)

But this comes to pass, that the word might be fulfilled...—The words in italics are not found in the original, but they rightly complete the sense. For the phrase, “might be fulfilled,” compare Notes on John 12:38; John 13:18.

That is written in their law.—Compare Note on John 10:34.

They hated me without a cause.—The passage immediately referred to is probably that of the Messianic Psalm (Psalms 69:4). The words are found also in Psalm 35:19 (see marginal reference), and less distinctly in Psalm 109:3; Psalms 119:161. (Compare especially Note on the quotation from this same Psalm in John 2:17.)

The words, “without a cause,” rightly express the meaning of the Hebrew word in the Psalm. The Greek follows the LXX, which expresses the thought “to no purpose,” or “in vain.” This is, however, not the idea of the context here. They had no reason for their sin, and therefore they hated Him without a cause. True were these words of many an earlier sufferer; but they were in their fullness true, they were “fulfilled,” only in the one sinless Sufferer.