To sail by Ephesus - The word “by” in our translation is ambiguous. We say to go by a place, meaning either to take it in our way and to go to it, or to go past it. Here it means the latter. He intended to sail past Ephesus without going to it.
For he hasted ... - Had he gone to Ephesus, he would probably have been so delayed in his journey that he could not reach Jerusalem at the time of Pentecost.
The day of Pentecost - See the notes on Acts 2:1.