Returning Whole and in Peace

Rashi:" and He will give me bread to eat"
As He said, "for I will not forsake you" for if one must seek bread, he is called "forsaken," as it is said: "I have not seen a righteous man forsaken and his seed seeking bread. (Ps. 37:25)
...that no disqualification should be found among my seed...
"and the L-rd will be my G‑d"
that His name will rest upon me from beginning to end, that no disqualification should be found among my seed, as it is written: "[I will do] that which I have spoken concerning you." And this promise He promised to Abraham, as it is said: "to be a G‑d to you and to your seed after you." (17:7) ("Your seed" means that they should be of pure lineage, that no disqualification should be found in him.)

Baal HaTurim: "to wear"
This word appears twice in Scripture: (1) here and (2) with regard to the mitzvot required of a High Priest: "to wear the vestments". (Lev. 21:10) This teaches that Jacob served as the High Priest as stated in the Midrash: "G‑d told the angel Michael, "You blemished Jacob, My High Priest, "for he is limping on his hip". (32:32) I swear you must serve as High Priest in heaven in his place." That is what Jacob meant when he said, "If G‑d will give me bread to eat and clothes to wear." He was asking, "May the priesthood which I got from Esau be maintained for me," for the altar service was granted to the firstborn until the sin of the Golden Calf.

Ramban: "If G‑d be will be with me"
alludes to the future center of worship for all Israel, the central meeting place, House of G‑d; the Temple below parallels the Temple above. Pure Jacob will rest on the pure Land to attach to G‑d’s possession. The Temple is malchut, and land is malchut, the Chosen House is malchut, The special place for the Ark in the central point of land is tiferet, the midpoint, Israel is atarah/crown, G‑d of the land of Israel, G‑d of Jerusalem. "He who dwells outside of the land of Israel is like one who has no G‑d", (Ketubot 110b) so the Eternal will be [fully] the G‑d of Jacob only when he returns to the Land of Israel.

Ohr HaHayyim: "Then the L-rd will be my G‑d"
This sounds G‑d forbid as if until then the L-rd had not been Jacob's G‑d! Rashi explains that Jacob meant that G‑d would not find any of his children as morally unfit. I do not know where such a thought is alluded to in Jacob's words. Besides such a promise is at best a conditional promise. And when would the stone be able to serve as a monument for this encounter that Jacob had during his dream?

The proper explanation is that Jacob was prepared to conduct himself in such a way that G‑d would consent to associate His name with him even during his lifetime. He had previously done this with Abraham after the latter's death and with Isaac only after he became blind and outside of the reach of the Evil Inclination. The words "Then the L-rd will be my G‑d " are clear evidence of Jacob's intention. This was a tremendous undertaking. You will find later (Gen. 33:20) that G‑d reminded Jacob of this undertaking and that Jacob fulfilled this vow by erecting a monument in his honor.

Zohar Vayetze 150:
"And Jacob vowed a vow, saying, If Elokim will be with me..." (Gen. 28:20) Rabbi Yehuda said: Although G‑d promised him all that, why did Jacob not believe this? Rather, he questioned, "If Elokim will be with me...?" Only Jacob said, 'I have dreamed a dream, and some dreams are true, and some are not. If the events in the dream come to pass, then I shall know that the dream is true.'
Jacob said, '...some dreams are true, and some are not...'
Similarly Jacob. However, do not say that he did not trust G‑d. It is not so. He simply did not believe in himself, and he was afraid that he might sin and that would prevent him from returning home in peace. And as a result, the keeping would be removed from him. Therefore, he did not trust himself. "And Havaya will be to me for Elokim " means when I will return in peace, I will put even mercy before judgment, so I will worship Him always.