Or HaChaim on Genesis 29:21/אור החיים על בראשית כ״ט:כ״א

1 ויאמר יעקב הבה לי אשתי, Jacob said: "hand me over my wife, etc." The reason that Jacob added the (uncouth sounding) words "so that I can have physical relations with her," something that even an uneducated person would not say, much less a person of Jacob's learning and sensitivity, can be explained by reference to Maimonides in chapter five of his Hilchot Ishut. If someone declares to his bride to-be: "you are betrothed to me in exchange for certain work I shall perform for you and he performs this work, this is not a valid form of betrothal since the compensation the bride receives (the work) is considered as a loan only, and one cannot acquire a bride by means of a loan." This is why Jacob said: הבה, "hand over!" Up until he had completed the work contracted for, Rachel had not even been his betrothed. Jacob was aware that he had not acquired Rachel by means of the value of the work he performed for Laban. As a result he could acquire her only by means of having physical relations with her. He therefore had to ask Laban to make this possible by handing her over, i.e. ואבא אליה.

2There is another way to solve our problem. We know that both Rachel and Leah told Jacob later on that their father considered them as strangers whom he had sold (Genesis 31,15). Concerning the laws of purchase of properties or slaves Maimonides writes in Hilchot Mechirah chapter 7 that if one acquires either slaves or real estate by means of a loan such a purchase is valid even if no money changes hand at the time. When Jacob said to Laban הבה את אשתי he meant that inasmuch as Rachel had already become his wife at the beginning of his servitude because he thought that he had "bought" her (in accordance with Maimonides), there was no need for actual money to change hands. The words הבה לי were not to be understood as the final act in the acquisition of Rachel as a wife, but were to be the prelude to his fulfilling his marital duties with a woman already his wife. He added the words ואבא אליה to preclude any pretense by Laban that Rachel was not yet his legally acquired wife.