Genesis 28:13

נצב עליו STOOD ABOVE HIM to guard him (Genesis Rabbah 69:3). ואלהי יצחק AND THE GOD OF ISAAC — Although we do not find in the Scriptures that God associates his Name with that of the righteous whilst they are yet alive by writing, “The God of so-and-so”, — because it is said (Job 15:15) “Behold He putteth no trust even in His holy ones” — here, however, He associated his Name with that of Isaac because his eyes had become dim and he was confined to the house, so that he might be regarded as dead and as though the evil inclination had already passed away from him and he was unlikely to sin any more (Midrash Tanchuma, Toldot 7). שכב עליה THE LAND WHEREON THOU LIEST — The Holy One, blessed be He, rolled together the entire Land of Israel under him, thus intimating to him that it would be as easily conquered by his descendants (Chullin 91b) as a piece of land four cubits in length, which is the space covered by a person lying down (see Rashi, Chullin 91b, and the note of the ב"ח thereon).

וְהִנֵּ֨ה יְהֹוָ֜ה נִצָּ֣ב עָלָיו֮ וַיֹּאמַר֒ אֲנִ֣י יְהֹוָ֗ה אֱלֹהֵי֙ אַבְרָהָ֣ם אָבִ֔יךָ וֵאלֹהֵ֖י יִצְחָ֑ק הָאָ֗רֶץ אֲשֶׁ֤ר אַתָּה֙ שֹׁכֵ֣ב עָלֶ֔יהָ לְךָ֥ אֶתְּנֶ֖נָּה וּלְזַרְעֶֽךָ׃

And, behold, the Lord stood above it, and said, I am the Lord God of Avraham thy father, and the God of Yiżĥaq: the land on which thou liest, to thee will I give it, and to thy seed;