Is it permissible to stop one's regular monthly charity due to financial hardship, or must one continue it despite the hardship?

The intention to give charity does not make it obligatory. Rather, it becomes obligatory through a vow (nazr) that requires a specific verbal declaration indicating commitment, and it is not established by mere intention. One should continue to give charity as long as they are able. If they cannot find anything to donate, Allah will record for them what they used to do when they were able, as stated in the hadith: "If a servant falls ill or travels, what he used to do when he was healthy and at home will be recorded for him." This applies to someone who was performing an act of obedience but was prevented from it, and their intention was to continue doing it.