As we have learned, the true purpose for which the Torah allows a father to “sell” his daughter as an amah ivriyah is for the “master” to have his son (or himself) marry the girl. In this case the marriage is called yi’ud (see Shemot 21:9). Rabba bar Avuha raises the following question about yi’ud – is it nisu’in or is it eirusin? The Gemara points out that the practical differences between these two possibilities will be whether he has the ability to be mefer her nedarim (see Massekhet Nedarim, daf 67), Furthermore, in the event that she dies, will the husband inherit her property, or, if he is a kohen, will he be obligated to participate in her burial.
Several explanations are offered to explain why yi’ud may effectively complete the marriage. The Me’iri quotes the Ra’avad as comparing the case of amah ivriyah to a case of maser ha-av le-sheluhei ha-ba’al – when, in a regular case of a marriage arranged by the father, the father transfers his daughter into the hands of the husband’s messengers. That messirah – “handing over” – effectively moves the bride into her husband’s domain, completing the marriage. Similarly in our case, the amah ivriyah has been moved into her husband’s domain, and the nisu’in is complete. The Pnei Yehoshua suggests that since the amah ivriyah is living in the same house as her betrothed, who can consummate the marriage at any time, we could conceivably view her as having had nisu’in.
The Rambam (Hilkhot Avadim 4:9) rules that yi’ud only accomplishes eirusin, so the marriage will only be completed with appropriate nisu’in – the symbolic ḥuppah (wedding canopy) that will bring her into his home as his wife.