John Lightfoot on John 15:6

[As a branch.] See Ezekiel 15:2, where D. Kimchi paraphrases in this manner: "O Son of man, I do not ask thee concerning the vine that beareth fruit (for so it ought to be accounted), but concerning the branch which is amongst the trees of the wood, unfruitful, even as the trees themselves are." Where, by branch (for so it is commonly rendered), we are to understand the wild vine. So R. Solomon in loc.: "I do not speak (saith God) of the vine in the vineyard that bears fruit, but of the branch of the wild vine that grows in the woods." So that the sense of the prophet is, "O son of man, what is the vine tree more than any tree?" viz. a branch of the wild vine which grows amongst the trees of the forest, which is unfruitful, even as they are.

And this is our Saviour's meaning; "Every branch in me that bringeth not forth fruit is cast forth like the branch in the vine that grows wild in the forest, which is good for nothing but to be burned"...