Ethically you need aclu.

You should team up and form a strong voice that you will use to disseminate your demand for pay through media and other communication channels like... community meetings. The concerned authorities will learn of it, may attract their attention, and they will take action against the man  more

You agreed to help a neighbor. What are you complaining about yet there is no agreement for remuneration.

Put up notices everywhere you can to prevent him from doing this to anyone else

Need not to worry and take a revenge on him by doing nothing but propagting his actions and comiitements to all in the village in a manner where it... should not be like complaint....Just smile at him and revoke the action what he did that to you....praise him personally for the activities he desreved at you and offer further assitance to him without debating advances....but this time ask for share from the harvest in written way  more

Remember, there is always the pillowcase option as a last resort.

Verbal contracts are binding if you have a witness.
Here is what you do...you get together with others who also entered into a verbal contract with... him and you all sue him together.
Your claim on its own might not hold merit, but multiple people making the same claim shows a pattern of behavior. more

No good deed goes unpunished. You volunteered to help him work on his farm. That means you are a good person. That he regularly does this to people... simply means you're a better person than he. Take comfort in that knowledge, learn from the experience, and move on. more

Write him an email. Demand payment, and exaggerate how much he owes you. If he owes you $1200, claim he owes you $2000. He will respond saying he... only owes you $1200. There. You have it in writing. more

It's very I hear

In any commercial relationship, there should be a clear understanding of the terms of the relationship expressed in a writing. The better rule, I've... found, is not to do business with friends and neighbors. Chalk this one up to experience and don't harbor a grudge. I recommend trying to maintain at least a civil relationship with the neighbor. Grudge harboring is more a burden to you than your neighbor.  more

Unfortunate that you had to go through this. I understand that in small communities or villages goodwill is vital and that is used as a currency for a... lot of things we do for one another. Even out these communities, we depend to do things, you don't always need signed contracts. What was done to you was unethical and unacceptable.
The good thing is that, verbal agreements are enforceable and also it did happen to only you. There is strength in numbers so I will suggest you join together with the other aggrieved and bring it to the attention of the local chiefs, clerics or youth authority. Class action also counts, if a number of you gather to report it at the police they will definitely take it up and make sure the right thing is done.
In the interim, Look around you and find some of the challenges that your community faces and try to solve it at a token. All the best. more