Sefer HaChinuch ספר החינוך

That a groom should not go out from his home the whole year, even for the needs of the community: That the groom is prevented from going out from his house the entire [first] year, meaning to say to go on distant trips. And also the army officer is prevented from taking him out by force, meaning to say, from taking him out to war or to do work needed for the war — for example, to supply water and food to his brothers or to fix matters in the city, to guard it from the enemy. And about this is it stated (Deuteronomy 24:5), “nor have any purpose assigned to him.” And they said in Tractate Sotah 44a, “‘He shall not go out with the army’ — it is possible that with the army he shall not go out, but he should fix weapons or supply water and food; [hence] it is taught to say, ‘nor have any purpose assigned to him.’” And they inferred further, “[it is] ‘to him’ that you do not assign, but you do assign to others,” meaning to say to those that return from the war because of weak-heartedness, or because of the dedication of a house or vineyard. And there they also said, “And since it comes out from ‘nor have assigned to him,’ why do I have ‘he shall not go out with the army?’ To have him transgress on two negative commandments.”

And I have already written that which is needed about this commandment, according to the fashion of the book, in its positive commandment in this Order (Sefer HaChinukh 582) — take it from there.