Is spending on one's family considered sufficient charity, precluding the need to give charity to others, and is retaining some money in anticipation of emergencies considered an error, even though sustenance is in God's hands?

There is no sin upon you for not giving charity, as charity is a recommended act, not an obligatory one. However, if the savings you possess reach the nisab (minimum threshold) and a full year passes over them, then zakat becomes obligatory. It is permissible to save money, as the Prophet, peace and blessings be upon him, used to save a year's provisions for his family. Spending on oneself and one's family is obligatory and is considered a form of charity, as is spending on one's siblings, which is both charity and an act of maintaining kinship ties. The Prophet, peace and blessings be upon him, said: "Begin with yourself and give charity to it; if anything is left over, then for your family; if anything is left over from your family, then for your relatives; if anything is left over from your relatives, then for such and such." He also said: "O son of Adam, that you spend what is in excess is better for you, and that you withhold it is evil for you, and you are not blamed for a sufficiency. Begin with those whom you support, and the upper hand is better than the lower hand." Al-Nawawi explained that spending what is in excess of one's needs is better for you due to the perpetuity of its reward, and withholding it is evil. There is no blame for possessing what is sufficient for one's needs, as long as no religious right, such as zakat, is attached to it.