This sentence strongly suggests an urban legend (modern tale) or a short story that often circulates on social media or as an inspirational anecdote, but has no corroboration in historical documents about actual executions.

The narrative usually describes a situation in which a condemned inmate makes one final request shortly before his execution—often an unusual or seemingly inconsequential request. The subsequent bark that changes everything usually leads to a pardon or stay of execution because it:

Is a sign or sound associated with the condemned inmate’s innocence (e.g., the barking of his own dog, which he referred to as his “witness”).
Is a chance event that causes officials to pause, and during this time, a pardon or reprieve arrives.
Conclusion:

This is most likely a fictional story with a moralizing point (often about the power of hope, justice, or an innocent witness), not a verified historical incident.

The search results do not contain any historical accounts or news articles that corroborate this specific story of the plea, the barking, and the thwarted execution. The results only cover general topics such as death row inmates, executions, and dogs in historical or fictional contexts.