What were the things that the Prophet, may Allah's peace and blessings be upon him and his family, would not refuse, and what is the ruling on people refusing them?

The Prophet, peace and blessings be upon him, used to accept gifts and reward for them, and he would accept good things and not refuse them. The Prophet, peace and blessings be upon him, commanded that a Muslim accept kindness that comes to him without his asking for it, and he forbade its refusal, for it is sustenance that Allah has brought to him. It is disliked to refuse a gift or a good thing, unless there is a valid Shariah-compliant impediment, and sometimes its refusal may even be obligatory.