If I understand Deuteronomy 14:12ff, that tenth of the produce that an Israelite was to give to YHWH actually goes into his own stomach.
22 Be sure to set aside a tenth of all that your fields produce each year. 23 Eat the tithe of your grain, new wine and oil, and the firstborn of your herds and flocks in the presence of YHWH your God at the place he will choose as a dwelling for his Name, so that you may learn to revere YHWH your God always. 24 But if that place is too distant and you have been blessed by YHWH your God and cannot carry your tithe (because the place where YHWH will choose to put his Name is so far away), 25 then exchange your tithe for silver, and take the silver with you and go to the place YHWH your God will choose. 26 Use the silver to buy whatever you like: cattle, sheep, wine or other fermented drink, or anything you wish. Then you and your household shall eat there in the presence of YHWH your God and rejoice.
Deuteronomy 14:28-29 indicates that an additional third of a tenth goes to the Levites and the needy:
28 At the end of every three years, bring all the tithes of that year's produce and store it in your towns, 29 so that the Levites (who have no allotment or inheritance of their own) and the aliens, the fatherless and the widows who live in your towns may come and eat and be satisfied, and so that YHWH your God may bless you in all the work of your hands.
Although the Israelites, when moving into the promised land, were to totally slaughter all the inhabitants of the land, that rule did not hold for cities outside of the promised land:
10 When you march up to attack a city, make its people an offer of peace. 11 If they accept and open their gates, all the people in it shall be subject to forced labor and shall work for you. 12 If they refuse to make peace and they engage you in battle, lay siege to that city. 13 When YHWH your God delivers it into your hand, put to the sword all the men in it. 14 As for the women, the children, the livestock and everything else in the city, you may take these as plunder for yourselves. And you may use the plunder YHWH your God gives you from your enemies. 15 This is how you are to treat all the cities that are at a distance from you and do not belong to the nations nearby.
16 However, in the cities of the nations YHWH your God is giving you as an inheritance, do not leave alive anything that breathes. 17 Completely destroy them—the Hittites, Amorites, Canaanites, Perizzites, Hivites and Jebusites—as YHWH your God has commanded you. 18 Otherwise, they will teach you to follow all the detestable things they do in worshiping their gods, and you will sin against YHWH your God.
When attacking a city, the Israelites could cut down non-food-bearing trees to use in their attack, but they could not chop down food-bearing trees:
19 When you lay siege to a city for a long time, fighting against it to capture it, do not destroy its trees by putting an ax to them, because you can eat their fruit. Do not cut them down. Are the trees of the field people, that you should besiege them? 20 However, you may cut down trees that you know are not fruit trees and use them to build siege works until the city at war with you falls.
And that, boys and girls, is today's Bible lesson from the Tanahk. (The "Tanahk" is the name used by Jews for what we call the "Old Testament", and is derived from the letters T, N, and K, which were the starting letters of the Hebrew words for "the Law, the Prophets, and the Writings".)