Sotah, Chapter 8, Mishnah 4. Our Mishnah lists those people who do not go out to war at all: "V'eilu she'ein zazin mimkoman" - these do not move from their place and do not go out to the battlefield at all, not even to hear the words of the kohen anointed for war and then return.
Those who do not move from their place:
"Banah bayis v'chanacho" - one who built a new house, dedicated it and began living in it, but has not yet lived in it for a full year.
"Nata kerem v'chillelo" - one who planted a vineyard (or another kind of fruit tree), and the fourth year arrived, but the entire fourth year has not yet been completed.
"Hanosei es arusaso" - one who marries his betrothed, the woman with whom he has already made kiddushin. And likewise "hakoneis es yevimto" - one who marries his yevamah. During the first year they do not go anywhere.
The source of the law in the verse:
"Shene'emar: naki yihyeh l'veiso shanah achas" - that he shall be free for one year for his house. From the wording of the verse the Mishnah derives and includes all of these cases:
"L'veiso" - this is his house, the new house that he built.
"Yihyeh" - this word comes to include his vineyard, that it too has a year.
"L'samei'ach es ishto" - this is his wife.
"Asher lakach" - to include his yevamah. These words, which seem superfluous, come to teach that even if she is his yevamah, he has a year.
The scope of the exemption:
"Einam mesapkin mayim u'mazon v'ein metaknin es hadrachim" - they do not even supply the water and the food, and they also do not repair the roads. They are not involved at all, and they are completely exempt during that first year.
In summary: This Mishnah lists those who do not move from their place at all and do not go out to the battlefield even to hear the words of the kohen anointed for war: one who built a house and dedicated it, one who planted a vineyard and redeemed its fruit, one who marries his betrothed and one who marries his yevamah. It is all derived from the verse "naki yihyeh l'veiso shanah achas," and their exemption is absolute: not even supplying water and food, and not even repairing the roads.