Praise be to Allah.
The scholars of the four madhhabs are agreed that it is mustahabb for charity to be composed of whatever is surplus to one’s needs and the needs of those for whom one is responsible. If a person gives in charity that which affects his needs or the needs of those for whom he is responsible, that is a sin, because his spending on them is obligatory and it is not permissible to give precedence to a naafil (supererogatory) action over an obligatory one.
But with regard to whatever is surplus to the needs of those on whom a person is obliged to spend, the majority of scholars say that holding on to whatever wealth he needs is preferable to giving it all away in charity, unless he has an income or is sure that he will be able to put his trust in Allaah and be patient and steadfast in bearing poverty and will be able to refrain from begging. Some scholars regarded it as mustahabb to give all his wealth in that case. The Shaafa’is regard this as being the most correct view, and it is the apparent meaning of al-Muwaffaq’s words in al-Mughni. What may be understood from the Maaliki and Hanafi madhhabs is that they do not regard that as mustahabb, because after mentioning the above conditions concerning the permissibility of giving all one's wealth in charity, they say, “There is noting wrong with that,” as if the matter is permissible in their view. But some Maalikis add to that a comment which may be understood as meaning that they regard it as mustahabb, as they say, “The way of encouraging giving all one's wealth in charity is that the donor should feel good about it after giving all his wealth and should not feel regret about being without wealth or hope to gain a similar amount of wealth in the future. He should not have any need of it in the future for himself or for those on whom he is obliged or encouraged to spend. Otherwise it is not recommended for him (to give all his wealth in charity), rather it is haraam for him to do so if those on whom he is obliged to spend are in certain need, or it is makrooh for him to do so if he is certain that those on whom it is recommended for him to spend are in need, because it is better to give in charity that which is surplus to his needs and the needs of those on whom he is obliged to spend.”
(al-Mawsoo’ah al-Fiqhiyyah, 26/339)
From these comments it is clear that the scholars did not limit charity to one third (of one's wealth). The evidence from the Qur’aan and Sunnah that these scholars based their views on is as follows:
1 – The aayah (interpretation of the meaning):
“And let not your hand be tied (like a miser) to your neck, nor stretch it forth to its utmost reach (like a spendthrift), so that you become blameworthy and in severe poverty”
The mufassireen said, in their commentaries on this aayah: Do not give all that you have when you and your dependents are in need of it, so that you are left with no money to spend, like an exhausted camel, i.e., one which has lost its strength and has no energy. And it was said that it means, lest you be blamed and come to regret it. But the one who is being addressed here is not the Prophet (peace and blessings of Allaah be upon him), because he is not one of those who would regret spending what they had in their hands for the sake of Allaah. Rather Allaah forbade extravagance in spending and giving all the money that one has in hand, less that end in regret on the part of the one who spent all that he had.
2 – It was narrated that Ka’b ibn Maalik (may Allaah be pleased with him) said: “I said, ‘O Messenger of Allaah, as a sign of my repentance I will give away some of my wealth in charity to Allaah and His Messenger.’ The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘Keep some of your wealth for yourself, that will be better for you.’” (al-Bukhaari, 2552; Muslim, 4973).
The Prophet (peace and blessings of Allaah be upon him) did not specify that he should give one-third in charity.
Al-Shawkaani (may Allaah have mercy on him) said: “The hadeeth of Ka’b indicates that it is prescribed for the one who wants to give all his wealth in charity to keep some of it. That does not imply that if he wanted to go ahead with it, he would not be able to do so. It was said that giving all one's wealth in charity varies according to one's situation. If a person is strong and knows that he will be able to bear the consequences with patience, then there is no reason why he should not do that. Based on that we may interpret the action of Abu Bakr al-Sideeq and the way in which the Ansaar preferred others to themselves even though they were in need of that [cf. al-Hashr 59:9]. But if a person is not like that, then he should not do that. This is how the words “There is no charity except when one has the means” should be interpreted. According to another report, “The best of charity is that which is given when one has the means.”
3 – It was narrated that Anas ibn Maalik (may Allaah be pleased with him) said: Abu Talhah was the richest man among the Ansaar in Madeenah in terms of date palm trees, and the most beloved of his wealth to him was the garden of Bayruha’. It was opposite the Mosque and the Messenger of Allaah (peace and blessings of Allaah be upon him) used to go there and drink its water, which was good.”
Anas added: “When the aayah (interpretation of the meaning) –
‘By no means shall you attain Al-Birr (piety, righteousness — here it means Allaah’s reward, i.e. Paradise), unless you spend (in Allaah’s Cause) of that which you love’
[Aal ‘Imraan 3:92] –
was revealed, Abu Talhah stood up and went to the Messenger of Allaah (peace and blessings of Allaah be upon him), and said: ‘O Messenger of Allaah, Allaah says, “By no means shall you attain Al-Birr (piety, righteousness — here it means Allaah’s reward, i.e. Paradise), unless you spend (in Allaah’s Cause) of that which you love…” The most beloved of my wealth to me is the garden of Bayruha’, and I am giving it in charity to Allaah, hoping to find reward for that with Allaah. So dispose of it, O Messenger of Allaah, as Allaah shows you.’ The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘Bravo! That is a good deal, that is a good deal. I have heard what you said and I think that you should give it to your relatives.’ Abu Talhah said, ‘I will do that, O Messenger of Allaah.’ So Abu Talhah shared it out among his relatives and cousins (sons of his paternal uncles).”
(al-Bukhaari, 1368; Muslim, 1664)
Al-Shawkaani (may Allaah have mercy on him) said (al-Nayl, 3/36):
“This indicates that it is permissible to give more than one third of one’s wealth in charity when one is alive and not suffering from terminal illness, because the Prophet (peace and blessings of Allaah be upon him) did not ask Abu Talhah how much he wanted to give in charity, but he said to Sa’d ibn Abi Waqqaas when he was sick, “A third is a lot.”.