What is the meaning of "Im be'Gapo Yavo be'Gapo Yeitzei"?
Rashbam: It is a general statement - inasmuch as, if he came in single, a. he leaves single seeing as there is no wife to leave with him), and b. even if his master then gives him a 'wife' (a Shifchah Cana'anis) - he goes out alone. 3
Moshav Zekenim (2) #1: The Parshah can discuss Hashem acquiring Yisrael. If one is without Torah and Mitzvos in this world, he leaves this world without merit. "Im Ba'al Ishah Hu" - if he engaged in Torah, it accompanies him. "Im Adonav Yiten Lo Ishah" - if he engaged in Torah Lo Lishmah (for reward), he leaves this world without merit; his Torah becomes lethal poison for him. 4 If he loves his Master, and loves his wife (learns Torah Lishmah), "v'Higisho Adonav El ha'Elokim" - he will behold the Shechinah [after death] and serve "l'Olam" (merit Techiyas ha'Mesim).
Moshav Zekenim #2: The letters of b'Gapo spell b'Guf, for one without a wife is like a fleeting bird.
To whom does "Im Ba'al Ishah hu" refer?
Mechilta: It refers to his real wife. 1
Mechilta: Since the wife that his master gives him is discussed in the next Pasuk.
What does the Torah mean when it concludes "Im Ba'al Ishah hu, Veyatz'ah Ishto imo"?
Rashi and Ramban (citing the Mechilta): By inference, it means that someone who purchases an Eved Ivri, is obligated to feed him and his wife and children, 1 and that, when the Eved Ivri leaves, this obligation automatically terminates.
Moshav Zekenim (Al Derech Derush): Refer to 21:3:1:3.
Ramban: We learn from "Imo" that as long as the husband is working for him, whatever his wife and (small) children produce belongs to the master - though the woman is not bound by this deal, should she prefer to remain independent (And he adds that this is also the opinion of Rashi in Kidushin, 22a). See Ramban DH 've'Chol Zeh', who elaborates further.
Why does the Torah insert "Ishto Imo"?
Mechilta: "Ishto" precludes the master from having to feed the Eved Ivri's Shomeres Yavam, and "Imo" precludes his Arusah.
QUESTIONS ON RASHI
Rashi writes that one who buys an Eved Ivri must feed also his wife and children. What is the source? The Torah did not mention children here!
Da'as Zekenim, Hadar Zekenim: The one who holds that there is no Gezeirah Shavah [equating one who sold himself and one that Beis Din sold him], this is a Giluy Milsa.
Moshav Zekenim - a father himself must feed only very small children (under six), and all the more so a master! Toras Moshe - here the Torah did not hint to this, for any children at the time the sLa'ave was sold reach six years before the sLa'ave is freed, and they left before him. Vayikra 25:41 discusses going free in Yovel; this can be within six years, and his children who are less than six leave with him. It seems that Gur Aryeh disagrees. Refer to 21: 3:153:1 and the note there.
Rashi writes that if he came in single, his master may not give to him a Shifchah to live with. It is more reasonable to permit this if the sLa'ave is single!
Moshav Zekenim #1: A man finds contentment only from his first wife and children. If his first 'marriage' was to a Shifchah, he would not want to leave her, and would be Nirtza. The Torah wants him to be a sLa'ave only to Hashem!
Moshav Zekenim citing R. Yehudah ha'Chasid: If a bachelor could marry a Shifchah, one might see a pretty Shifchah and sell himself in order to marry her. The Torah wants him to be a sLa'ave only to Hashem!
Moshav Zekenim #2: If he was not married and did not fulfill Peru u'Rvu yet 1 , the master may not give to him a Shifchah [lest he not marry someone else afterwards, and he will never fulfill Peru u'Rvu].
Chizkuni (4): When the master must feed the sLa'ave's wife and children, he may give a Shifchah to the sLa'ave, to receive baby sLa'aves from this union.
If he is married, his master may give to him a Shifchah even before he fulfilled Peru u'Rvu! At least he is making proper effort to fulfill it. We are not concerned lest he divorce his Yisraelis wife due to the Shifchah. (PF)
Rashi writes that one who buys an Eved Ivri must feed also his wife and children. The Torah did not obligate a man to feed his wife and children. Why is the master obligated more than a free man?