Sotah, Chapter 8, Mishnah 3. In the previous Mishnah we listed those whom the Torah releases from the ranks: one who built a new house, planted a vineyard or married a woman, and has not yet come to enjoy them - these return from the war. Our Mishnah comes to list the cases that are not included in this category.
Those who do not return from the war:
"HaBoneh beis sha'ar, achsadrah u'mirpeses" - one who builds a gatehouse for a courtyard, a portico (a roofed porch in front of the house) or a balcony of sorts. These structures are not significant enough to entitle their owner to return from the war.
"HaNotea arba'ah ilanei ma'achal" - one who plants only four trees, his planting does not count, since at least five are required.
"V'chamishah ilanei serak" - even if he planted five trees, if they are non-fruit-bearing trees they do not count.
Marriages that do not entitle one to return:
"HaMachazir es gerushaso" - one who remarries the very woman he divorced.
"Almanah l'kohen gadol" - a kohen gadol who marries a widow, who is forbidden to him.
"Gerushah va'chalutzah l'kohen hedyot" - an ordinary kohen who marries a divorcee or a woman who underwent chalitzah, who are forbidden to him.
"Mamzeres u'nesinah l'Yisrael" - a Yisrael who marries a mamzeres or a nesinah, who are forbidden to him.
"Bas Yisrael l'mamzer ul'nasin" - and likewise the reverse: a mamzer or a nasin who married a daughter of Yisrael does not return on account of such a marriage.
In each of these cases the Mishnah rules: "Lo hayah chozer" - he would not return.
The additions of the Tannaim:
"Rabbi Yehudah omer, af haboneh bayis al mechono lo hayah chozer" - one who builds a house on the very spot where the previous house stood, even though it is an ordinary house in every respect, does not return.
"Rabbi Elazar omer, af haboneh beis levenim ba'Sharon lo hayah chozer" - the brick houses in the Sharon region would crumble, and it was customary to rebuild them every seven years. Since they do not last, they are not considered permanent enough to rejoice in.
In summary: our Mishnah lists those whose building, planting or marriage does not entitle them to return from the war: one who builds a gatehouse, a portico or a balcony; one who plants four fruit trees or five non-fruit-bearing trees; and one who marries a woman forbidden to him or remarries his divorcee. Rabbi Yehudah added one who builds a house on its former site, and Rabbi Elazar added one who builds a brick house in the Sharon, which has no permanence.