When giving charity, should one give without fearing poverty i.e. should they give excessively, or should it be more moderate and taking into account how much you may need in the future etc?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Charity is either obligatory (Zakaah) or voluntary. As for the Zakaah, it is incumbent on a Muslim to pay the amount prescribed by the Sharee‘ah. As far as the Zakaah on gold, silver, cash, and trade goods, for example, are concerned, it is obligatory to pay one-fourth of one-tenth of its value (i.e. 2.5%). Likewise, a Muslim is required to pay the amount specified by the Sharee‘ah in every type of Zakaah. If he pays more than that amount as voluntary charity, there is nothing wrong with that.

As for voluntary charity, there is no specific amount prescribed by the Sharee‘ah that one is obliged to pay. A person may give in charity any amount he wishes, large or small. He may even give all his wealth in charity if he wishes, provided that it would not result in failure to provide for his dependents whom he is obligated to support, as per the Sharee‘ah, such as his wife and children, if any. The Prophet, sallallaahu ‘alayhi wa sallam, said: “It is sufficient sin for a man to neglect his dependents.” [Abu Daawood]

The Maaliki scholar An-Nafraawi said in his book Al-Fawaakih Ad-Dawaani: “There is nothing wrong if a sane adult person gives all his wealth in charity to the poor for the sake of Allah, seeking His reward in the Hereafter … The criterion of deeming it recommended for a person to give all his wealth in charity is that he should give it willingly and wholeheartedly such that he would not later regret becoming penniless, and that what he hopes to obtain in the future is similar to what he has given out now. Also, he should not be in need of it in the future for himself or his dependents for whom he is obligated to provide or on whom he is recommended to spend; otherwise, it is not recommended for him to give all his wealth in charity. Rather, it is prohibited for him to do so if his dependents whom he is obligated to support as per the Sharee‘ah are in need of it.” [End of quote]

Allah Knows best.