Sotah, Chapter Eight, Mishnah Four
Above in mishnah two we learned who returns from war if they are already out at battle. Those categories of people returned and worked in supplying food and water to the soldiers and in repairing the roads. In todays mishnah we learn those who dont go out to war in the first place and do not supply food or drink to the soldiers or fix the roads.
The idea that there are some soldiers who return home is connected to Deuteronomy 20:8, while the idea that some are not even obligated to go out in the first place is connected to 24:5, as we shall see below.
1) The following do not move from their place:
a) He who built a new house and dedicated it,
b) He who planted a vineyard and used its fruit,
c) He who married his betrothed,
d) Or brought in his yevamah;
2) As it is said, He shall be exempt one year for the sake of his household [to give happiness to the woman he married] (Deuteronomy 24:5)
a) His household, this refers to his house;
b) Shall be refers to his vineyard;
c) To give happiness to the wife refers to his wife;
d) He married to include his yevamahs widow.
3) These do not supply water and food and repair the roads [for the army].
Section one: The Torah states that someone who is recently married does not go out to war for one year from his marriage. The rabbis take the categories mentioned in Deuteronomy 20, and discussed in the previous two mishnayoth, and apply them to this halakhah as well. Someone who built a new house and has already dedicated it, but has not lived in it for one year, is exempt from going to war. Similarly, one who planted a vineyard but has not enjoyed a years harvest need not go out to war. Finally, as the verse plainly states, a newly married man is exempt for one year. This also includes levirate marriage.
Section two: This section provides midrashic support for that which we learned above. The word his household does not just mean that he has a year to be with his new wife, as is the simple reading of the verse. Rather it also includes a new house that has not yet been dedicated. The word shall be includes a vineyard (this is a rather creative midrash). The wife refers to his wife. The verse did not need to state who he married since it already stated wife. Therefore the words he married are understood as including his yevamah (his levirate wife).
Section three: Deuteronomy 24:5 states, He shall not go out with the army or be assigned to it for any purpose. Therefore, not only is he exempt from fighting, but he is exempt from other duties as well.