Jamieson, Fausset and Brown on John 11:17-19

17-19. when Jesus came, he found that he had lain in the grave four days--If he died on the day the tidings came of his illness--and was, according to the Jewish custom, buried the same day (see Jahn's Archæology, and Joh 11:39; Ac 5:5, 6, 10)--and if Jesus, after two days' further stay in Perea, set out on the day following for Bethany, some ten hours' journey, that would make out the four days; the first and last being incomplete [Meyer].