זֵיתִ֛ים יִהְי֥וּ לְךָ֖ בְּכָל־גְּבוּלֶ֑ךָ וְשֶׁ֙מֶן֙ לֹ֣א תָס֔וּךְ כִּ֥י יִשַּׁ֖ל זֵיתֶֽךָ׃
Tu posséderas des oliviers sur tout ton territoire; mais tu ne te parfumeras pas de leur huile, car tes oliviers couleront.
Rashi
ישל means, it (the olivetree) shall drop its fruits. It is similar in meaning to the verb in (Deuteronomy 19:5), "And the iron falleth off (ונשל).
Ibn Ezra
annoint from “nor did I annoint myself at all” [Daniel 10: 3]. Scripture describes the situation that is the opposite of “oil upon your head” [Ecclesiastes 9: 8].
Rashbam
ישל, from the root נשל as in Deut. 7,1 ונשל גויים, “He will dislodge,” the construction is parallel to that of ימל קצירו in Job 18,16 compared to Genesis 17,11 ונמלתם, you shall circumcise.” The root נשך also becomes ישך in the future tense.