Olivet (Elaiōnos). Genitive singular. Vulgate Olivetum. Made like ampelōn. Here only in the N.T., usually to oros tōn Elaiōn (the Mount of Olives), though some MSS. have Olivet in Luk 19:29; Luk 21:37. Josephus (Ant. VII. 9, 2) has it also and the papyri (Deissmann, Light from the Ancient East, p. 170).
A sabbath day’s journey off (Sabbatou echōn hodon). Luke only says here that Olivet is a Sabbath day’s journey from Jerusalem, not that Jesus was precisely that distance when he ascended. In the Gospel Luke (Luk 24:50) states that Jesus led them “over against” (heōs pros) Bethany (about two miles or fifteen furlongs). The top of Olivet is six furlongs or three-fourths of a mile. The Greek idiom here is “having a journey of a Sabbath” after “which is nigh unto Jerusalem” (ho estin eggus Ierousalēm), note the periphrastic construction. Why Luke mentions this item for Gentile readers in this form is not known, unless it was in his Jewish source. See Exo 16:29; Num 35:5; Jos 3:4. But it does not contradict what he says in Luk 24:50, where he does not say that Jesus led them all the way to Bethany.