John 8:27 - Ellicott's Commentary On The Whole Bible

They understood not that he spake (better, was speaking) to them of the Father. — We have seen in Note on John 8:21 that a new discourse commences there, and that the hearers are not necessarily the same as those who had asked the question and heard the answer of John 8:19. Still the speakers then, and those spoken of now, are “the Jews” (comp. John 8:13; John 8:22); and they are probably in part identical with those of whom our Lord tells us there, that they knew neither Him nor the Father. Of these men St. John tells us now that they did not know that the Sender and the Father are one. The statement of their want of perception, which strikes us as so marvellous, is made just because it was marvellous. St. John remembers it many years afterwards, and remembers that on account of it Jesus proceeded to declare more fully that every act He did was done in the Father, and that every word He spoke was taught by the Father, and that in every event of His life the Father was present.