I am asking this question more from akherat point of view. No deal in writing. I had made a list of jobs to do and whatsaped him. He had verbally given the price. Now he is demanding more than double. If we give him it will be rizk e haraam for him coz it has been seen he lies too much. He has four children. I don't want them and him to be doomed in this world or akherat. So have asked. Also i don't want us to be questioned that why did you let him earn this unlawfully from you.

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If you can reason with him then ok but if not then it’s not your responsibility for his akhirat. He is responsible for his own.

You are not responsible since Quran says any agreement should be in writing. Without any written agreement there is no shari obligation on either side.