Musar for Berakhot 68:19

When the Midrash describes G–d as saying: "You are the vineyard and I am the watchman," this is a reference to the crown of monarchy as I have explained above. It is a reference to the gift of the World to Come, as I have already mentioned. Our sages are on record as saying: "All the prophets have prophesied only about the days of the Messiah (in this world); only G–d Himself has an idea of what the World to Come will be like" (Berachot 34). What has been reserved for revelation at that future time is called the יין המשומר, the wine which has been preserved (within its grapes) since the days before Adam was expelled from גן עדן. It is concerning this wine that G–d is portrayed as saying: "You are the vineyard and I am the keeper." The word שומר, refers to the wine which was preserved since the idyllic times when man was still at home in Gan Eden. When the time comes to partake from this wine, ביום ההוא אקים את סוכת דוד הנופלת, "On that day I will re-establish the broken down hut of David" (Amos 9,11). This is why G–d is quoted in the Midrash as asking Israel to build a hut for Him. When Israel erects a hut in our domain, the hut of David which has collapsed can be rebuilt in the corresponding Celestial Regions. It will then advance spiritually ever higher until the mystical level of the emanation בינה, the root of עולם הבא, the World to Come, where the יין המשומר is carefully stored to prevent any Gentile touching it. The Gentiles' claim, if at all, to this עולם הבא does not extend beyond the domain of בנין, i.e. the emanations below בינה. The Gentiles' claim to any share in עולם הבא is based on Ishmael's descent from Abraham, whose outstanding characteristic was חסד, loving kindness. Esau's claim to any share in עולם הבא is similarly based only on the fact that he was the issue of patriarch Isaac. The reason that the Midrash did not bother to quote a verse confirming its claim is that the subject matter is עולם הבא, a subject scriptures have nothing to say about.