Musar zu Bereschit 17:6

Summing up, we find that the paragraph dealing with circumcision contains three great gifts 1) The kingdom of David will endure forever. 2) The gift of the land of Israel to the Jewish people will be a permanent possession of the people. 3) The Presence of G–d will rest visibly over the people and the land of Israel. Concerning the first promise Abraham is told ומלכים ממך יצאו והקמותי את בריתי, "kings will come forth from you; and I will maintain My covenant" (17,5). Correspondingly, we find in connection with the dynasty of David: כרתי ברית לבחירי, נשבעתי לדוד עבדי, עד עולם אכין, זרעך ובניתי לדור ודור כסאך סלה, "I have made a covenant with My chosen one; I have sworn to My servant David. I will establish your offspring forever, I will confirm your throne for all generations selah” (Psalms 89 4/5). Concerning giving the land of Israel to Abraham's descendants, G–d said: ונתתי לך ולזרעך אחריך את ארץ מגורך … לאחוזת עולם, "I will give to you and to your descendants after you the whole land of Canaan the land you sojourn in, as an eternal possession" (17,8). This means that even while we are in exile, the land will never be an inheritance of our enemies, but they will only be there on a temporary basis since it will be desolate while they occupy it. Once we shall return to it as an eternal possession the Presence of the שכינה will become manifest, and there will be fulfilled the last line of G–d's promise to Abraham "I shall be their G–d."