Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.086.
There is consensus that a deceased person benefits from all good deeds for which he or she in his or her life might have been a cause. Abu Hurairah reported, “The Prophet, peace be upon him, said, ‘When a person dies all his good deeds cease except for three: a continuous act of charity, beneficial knowledge, and a righteous son who prays for him’.” (Muslim, and the Sunan) Also Abu Hurairah reported, “The Prophet, peace be upon him, said, ‘The righteous works that continue to benefit a believer after his death include the knowledge that he taught and spread among others, a righteous son whom he leaves behind, or a copy of the Qur’an that he bequeaths to his inheritors, or a mosque that he builds, or a rest house that he builds for the wayfarers, or a canal of water that he digs for the benefit of others, or a charity that he gives out of his property during his life while he is sound of health. He will continue to receive reward for all these even after his death.’ (Ibn Majah)
Jarir ibn Abdallah reported: “The Prophet, peace be upon him, said: ‘Whoever introduces a good practice in Islam will get its reward and the rewards for all those who follow these practices after him, without any loss to their reward. And whoever introduces a bad practice in Islam will acquire its sin and the sins of all those who practice it, without any decrease in their sins.”
An account of the righteous deeds performed by others that continue to be beneficial to the deceased is given in detail below:
2. Charity. An-Nawawi has recorded that Muslim scholars agree that charity benefits the deceased person and its reward reaches the deceased whether it is given by his or own son or by someone else. This is based on a report from Ahmad, Muslim, and others from Abu Hurairah that, “A man said to the Prophet, peace be upon him, My father died leaving wealth but no will. Would he be pardoned if we gave charity on his behalf?’ He said: ‘Yes.”‘ It is also reported from Al-Hasan from Sa’d ibn ‘Ubadah that “his mother died and he said, ‘O Messenger of Allah, my mother has died. Should I give charity on her behalf?’ He said: ‘Yes.’ I said: ‘What is the best charity?’ He said, ‘Offering people a drink of water’.” Al-Hasan said: “This is the drinking place of the family of Sa’d in Madinah.” This is reported by Ahmad, Nasa’i, and others. Giving charity in the graveyard is not permissible and giving it during the funeral is disliked.
3. Fasting. This is based on a report by Bukhari and Muslim from Ibn ‘Abbas who said, “A man came to the Prophet, peace be upon him, and said, ‘My mother has died without making up for a missed month of fasting. Can I fast on her behalf?’ The Prophet, peace be upon him, said, ‘Would you pay her debt if she owed someone?’ The man said, ‘Yes.’ The Prophet, peace be upon him, said, ‘Allah is more deserving of payment in settlement of His debt’.”
4. Performing the Pilgrimage (Hajj). This is based on a report by Bukhari from Ibn ‘Abbas that “a woman of the Juhainah tribe came to the Prophet, peace be upon him, and said, ‘My mother had vowed to perform pilgrimage, but she died before she could fulfil her vow. Should I do it on her behalf?’ The Prophet, peace be upon him, said, ‘Yes. Perform Hajj on her behalf. Would you not pay the debt of your mother if she had owed someone? Fulfil it. Allah is more deserving of receiving payment for what is due to Him’.”
5. Prayer (salah). This is based on a report by Ad-Darqutni who said that “a man asked, ‘O Allah’s Messenger! I had parents whom I served while they lived. How can I be good to them after their death?’ The Prophet, peace be upon him, said, ‘Verily, among the good deeds that you can do after their death is to offer prayer (salah) for them when you pray for yourself and to fast for them when you fast for yourself’.”
6. Recitation of the Qur’an. This is beneficial to the deceased according to the opinion of the majority of the scholars among the ahl al-sunnah.
An-Nawawi said, “The most well-known position of the Shafi’i school is that this does not benefit the deceased.” Ahmad ibn Hanbal and a group of Shafi’i scholars hold that it does benefit the deceased. The reciter has an option. He may supplicate for the deceased to be rewarded for the recitation, saying: “O Allah! Grant the reward of what I recited to so-and-so.”
Ibn Qudamah in al-Mughni stated, “Ahmad ibn Hanbal said, ‘The deceased will receive the reward for every good done on his behalf. This is proved by textual evidence found on this subject. The fact that Muslims in every city gather to recite the Qur’an for the benefit of the deceased and that they have been doing so without any disagreement or disapproval show that there is consensus on this subject’.”
Those who hold that the deceased benefits by the recitation of others make it conditional upon the reciter not to accept any payment for his recitation. If the reciter is paid for reciting, it is unlawful for both the giver and the receiver, and he shall have no reward for his reciting. Abd Ar Rahman ibn Shibl reported that the Prophet, peace be upon him, said, “Recite the Qur’an, and do good deeds… Do not neglect it, nor be extreme in it. Do not make it a means of living nor a source of your wealth.” (Reported by Ahmad, At-Tabarani, and Al-Baihaqi)
Ibn al-Qayyim said, “Worship is of two types: financial and physical. The Prophet, peace be upon him, has informed us that because charity (sadaqah) benefits the deceased, all other acts of charity will also benefit the deceased, and that because fasting on his behalf benefits the deceased, all other physical acts of worship will likewise benefit the deceased. Similarly the Prophet, peace be upon him, informed us that the reward of making Hajj, which involves both physical and financial sacrifice, does indeed benefit the deceased. Thus these three types of beneficial acts of worship are supported by both the revealed texts and reason.”