The King James Version and NKJV says: “they departed after Paul had said one word”. But the main thing about that ‘word’ is: it was a statement with a quote from Isaiah 6:9-10. The better word for ‘word’ is of course ‘point’ in our current use of the word. It was a notion, an idea put forward by Paul to the stubborn Jews whom he was conversing and discussing with. 

I would go so far as to add [this] before ‘one point’. The main reasoning is εν (one) can bring a ‘certainty’ in contrast to just merely a numerical meaning (1), depending on the context. Reading the context of it being the ‘end of an arguement’ or at least the last say which Paul gives to the stubborn Jews, adding a ‘this’ to fix the reader to the point and reason for their departure is justified. 

At least it helps me in seeing the point of contention which made the Jews depart out of Paul’s presence.