What is the ruling on giving charity that diminishes the means of subsistence for dependents?

Primary text

If a person gives charity that falls short of what is required for the sustenance of those he is obligated to support, and he has no earning capacity, he commits a sin. This is established by the Prophet's saying: "It is enough of a sin for a man to neglect those he supports." Furthermore, the maintenance of dependents is obligatory, while voluntary charity is supererogatory; thus, prioritizing the supererogatory over the obligatory is impermissible.