Is an acknowledgment followed by a statement negating obligation valid?

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The initial acknowledgment of debt is upheld, and the subsequent negation is rejected, because the two statements inherently contradict each other. The very assertion that the debt exists conflicts with the assertion that it is not obligatory, similar to stating 'I owe a thousand that is not obligatory upon me' or stating 'I have paid all that I acknowledged,' which is rejected like excepting the entirety of the admitted sum.