Is a well-off Muslim obligated not to take charity, following the example of the Prophet (PBUH)?

Voluntary charity (sadaqat al-tatawwu') is not permissible to request except for those who are worthy of receiving it. However, it is permissible to take it if it comes without being requested, even if one is not in need of it, due to the Prophet's (peace be upon him) saying to 'Umar: "If something of this wealth comes to you and you are neither aspiring for it nor begging for it, then take it; otherwise, do not let your soul hanker after it."

However, it is not permissible to take it if the giver has earmarked it for a specific group to which the recipient does not belong, such as the poor and the needy. It must be noted that the Prophet's (peace be upon him) not taking charity is specific to him and his noble household.