Does the Prophet's (peace be upon him) saying: "A Muslim is one from whose tongue and hand people are safe," indicate the prohibition of practicing Taekwondo at home with siblings, if there is a possibility of accidentally causing pain, despite taking precautions and minimizing blows?

A Muslim is one from whose tongue and hand other Muslims are safe. Therefore, it is impermissible to harm a Muslim through word or deed. If a Muslim practices martial arts with the intention of harming a competitor, then he has not adhered to this principle. However, if practicing these sports results in significant harm without the intention of causing injury, then it is prohibited, because harming oneself or others is forbidden. But if the necessary precautions are taken to prevent harm, there is no objection to practicing the sport, even if it entails potential minor harm or slight damage that dissipates, for the purpose of strengthening and exercising the body, provided that it is not for harmful professional purposes. This is supported by what the Prophet, peace and blessings be upon him, did with Samurah ibn Jundub when he wrestled him and accepted his challenge, which indicates the permissibility of a certain agreed-upon degree of minor harm in the context of sports competition.