Geirus/Milah of Eved K'nani

ד] יֵשׁ מִקְנַת כֶּסֶף, שֶׁנִּמּוֹל לִשְׁמוֹנָה; וְיֵשׁ יְלִיד בַּיִת, שֶׁנִּמּוֹל בְּיוֹם שֶׁנּוֹלַד. כֵּיצַד: לָקַח שִׁפְחָה וְלָקַח עֻבָּרָהּ עִמָּהּ וְיָלְדָה, הֲרֵי זֶה נִמּוֹל לִשְׁמוֹנָה; וְאַף עַל פִּי שֶׁלָּקַח הָעֻבָּר בִּפְנֵי עַצְמוֹ, וַהֲרֵי הָעֻבָּר עַצְמוֹ מִקְנַת כֶּסֶף, הוֹאִיל וְקָנָה אִמּוֹ קֹדֶם שֶׁתֵּלֵד, נִמּוֹל לִשְׁמוֹנָה

The Rambam here is discussing two types of eved k'nani. One is called a miknas kesef, and eved who is bought as a slave. The other is a yilid bayis, an eved who is born into servitude. The general halacha is that eved k'nanim have a milah done to them. (Essentially, they become Jewish and are chayav in mitzvos the same way women are.)
In a normal case, a miknas kesef is nimol on the day he is bought. The Rambam here is bringing an exception to this rule. If one buys a shifcha with her fetus. In such a case it is really a miknas kesef, but he is nimol lishmoneh because he is born in the reshus ha'adon.

The Rambam then brings a second case:

ה] לָקַח שִׁפְחָה לְעֻבָּרֶיהָ, אוֹ שֶׁלָּקַח שִׁפְחָה עַל מְנָת שֶׁלֹּא לְהַטְבִּילָהּ לְשֵׁם עַבְדוּת--אָף עַל פִּי שֶׁנּוֹלַד בּרְשׁוּתוֹ, נִמּוֹל בְּיוֹם שֶׁנּוֹלַד: שֶׁהֲרֵי הַנּוֹלָד הַזֶּה כְּאִלּוּ הוּא מִקְנַת כֶּסֶף לְבַדּוֹ, וּכְאִלּוּ הַיּוֹם קָנָהוּ, שְׁאֵין אִמּוֹ בִּכְלַל שִׁפְחוֹת יִשְׂרָאֵל, כְּדֵי שֶׁיִּהְיֶה הַבֵּן יְלִיד בַּיִת. וְאִם טָבְלָה אִמּוֹ אַחַר שֶׁיָּלְדָה, הֲרֵי זֶה נִמּוֹל לִשְׁמוֹנָה

Here the Rambam says that if one buys a fetus with no intention of buying the mother with it, he gets a milah on the day he is born. Why? Because in such a case he has a din of a miknas kesef because he is essentially a bought slave.

The Rambam seems to be saying as follows: Really a miknas kesef is nimol on the day he is bought. However, if the mother is bought along with the fetus, the status is in effect a yilid bayis. This is because by owning the mother it's as though the eved is born into the service. Also, a yilid bayis is nimol l'shmoneh. However, if the mother is not bought along with the fetus, it is in reality a miknas kesef. Again, this is because by not owning the mother, it is by definition miknas kesef. Everything is dependent on whether the master owns the mother or not.

This brings us to the last Rambam:

י] כְּשֵׁם שֶׁמִּילַת הַבָּנִים, דּוֹחָה אֶת הַשַּׁבָּת; כָּךְ מִילַת הָעֲבָדִים שְׁהֶן נִמּוֹלִין לִשְּׁמוֹנָה--דּוֹחָה אֶת הַשַּׁבָּת, אִם חָל שְׁמִינִי שֶׁלָּהֶן בַּשַּׁבָּת: חוּץ מִיְּלִיד בַּיִת שֶׁלֹּא טָבְלָה אִמּוֹ עַד שֶׁיָּלְדָה--שֶׁאַף עַל פִּי שֶׁנִּמּוֹל לִשְׁמוֹנָה, אֵינוּ דּוֹחֶה אֶת הַשַּׁבָּת.

Here we have a very interesting halacha. If one has a yilid bayis, but the mother doesn't do a tevilah until after the baby is born, the halacha is that it is nimol l'shmoneh. In other words, it is enough to own the mother to make it a yilid bayis. The fact that the mother delays her tevilah is irrelevant. (The is against an opinion in the gemara that holds that the fact that the mother delays her tevilah makes it a case of nimol l'echad, see Shabbos 135b.)

Yet, even though the Rambam says that the baby is nimol l'shmoneh, still the bris is not docheh shabbos. The question is why. If the fact that the mother wasn't tovel doesn't affect the status of the baby, and the baby is still a yilid bayis that is nimol l'shmoneh, so why isn't that bris docheh shabbos?

Rav Chaim deals with this question in Hilchos Milah 1:10. We will iy"h continue this topic in a future post.