Fear of one’s good deeds being rendered invalid and having a tough reckoning on the Day of Resurrection is one of the most serious thoughts that give the righteous sleepless nights and prevent many of the pious close friends of Allah from sleeping comfortably. Because of it tears have flowed from the eyes of worshippers whose hearts Allah, may He be glorified and exalted, described as being full of fear, and He praised them for hastening to do good deeds. This is seen in the verse in which He, may He be glorified and exalted, says (interpretation of the meaning):

“And those who give that (their charity) which they give (and also do other good deeds) with their hearts full of fear (whether their alms and charities, etc., have been accepted or not), because they are sure to return to their Lord (for reckoning).

It is these who race for the good deeds, and they are foremost in them (e.g. offering the compulsory Salah (prayers) in their (early) stated, fixed times and so on).”

[al-Muminoon 23:60-61]. 

It was narrated that ‘Aishah (may Allah be pleased with her) said:

I asked the Messenger of Allah (peace and blessings of Allah be upon him) about this verse (interpretation of the meaning): “And those who give that (their charity) which they give (and also do other good deeds) with their hearts full of fear” [al-Mu’minoon 23:60]. ‘Aa’ishah (may Allah be pleased with her) said: Are they those who drink alcohol and steal? He said: No, O daughter of as-Siddeeq; rather they are the ones who fast and pray and give charity, but they fear that it will not be accepted from them; they are the ones who race for the good deeds.” 

Narrated by at-Tirmidhi, no. 3175; classed as saheeh (authentic) by Ibn Katheer in Tafseer al-Quran al-‘Azeem, 1/176. 

Despite this, the feelings of fear – in these people – did not turn into constant anxiety that prevents one from striving or makes one despair, and it did not turn into insinuating thoughts (waswas) that are contrary to what one may understand from dozens of verses of hope in the Holy Quran. 

Have you not heard the words of Allah, may He be glorified and exalted (interpretation of the meaning):

“Surely! Allah wrongs not even of the weight of an atom (or a small ant), but if there is any good (done), He doubles it, and gives from Him a great reward.”

[an-Nisa 4:40]

And Allah, may He be glorified and exalted, says (interpretation of the meaning):

“Whosoever brings good (Islamic Monotheism along with righteous deeds), he shall have the better thereof, and whosoever brings evil (polytheism along with evil deeds) then, those who do evil deeds will only be requited for what they used to do.”

[al-Qasas 28:84]

“Verily! As for those who believe and do righteous deeds, certainly! We shall not suffer to be lost the reward of anyone who does his (righteous) deeds in the most perfect manner.

These! For them will be Adn (Eden) Paradise (everlasting Gardens); wherein rivers flow underneath them, therein they will be adorned with bracelets of gold, and they will wear green garments of fine and thick silk. They will recline therein on raised thrones. How good is the reward, and what an excellent Murtafaqa (dwelling, resting place, etc.)!”

[al-Kahf 18:30-31]

“Certainly it is that one who pays obedience and shows perseverance, then surely Allah does not allow to go to waste the reward of those who do good in perfection.”

[Yoosuf 12:90].

What the Muslim is required to believe in – with real faith that is manifested in his actions and in his thoughts – is the justice and generosity of Allah and that He, may He be glorified and exalted, does not cause to be lost the reward of one who does good deeds, and He does not wrong anyone even the weight of an atom (or a small ant); rather He rewards good deeds with good, and He responds to bad deeds with pardon and forgiveness for whomever He will. 

Listen – O slave of Allah – to what your Lord says to us and His true words about Himself, may He be glorified, which He addresses to both hearts and minds (interpretation of the meaning):

“Why should Allah punish you if you have thanked (Him) and have believed in Him? And Allah is Ever All Appreciative (of good), All Knowing.”

[an-Nisa 4:174]. 

Fear of a bad reckoning and having one’s good deeds rendered invalid is one of the strongest means of creating a peaceful society in which people strive hard to do righteous deeds and acquire virtuous characteristics, as is stated in the Holy Quran in the verse quoted above, in which Allah, may He be glorified and exalted, says (interpretation of the meaning):

“And those who give that (their charity) which they give (and also do other good deeds) with their hearts full of fear (whether their alms and charities, etc., have been accepted or not), because they are sure to return to their Lord (for reckoning).

It is these who race for the good deeds, and they are foremost in them (e.g. offering the compulsory Sala (prayers) in their (early) stated, fixed times and so on).”

[al-Muminoon 23:60-61]. 

It is mentioned again when fear of a bad reckoning on the Day of Resurrection is mentioned alongside upholding ties of kinship and helping the poor and needy. That is in the verse in which Allah, may He be glorified and exalted, says (interpretation of the meaning):

“Those who join that which Allah has commanded to be joined (i.e. they are good to their relatives and do not sever the bond of kinship), fear their Lord, and dread the terrible reckoning (i.e. abstain from all kinds of sins and evil deeds which Allah has forbidden and perform all kinds of good deeds which Allah has ordained).”

[ar-Ra‘d 13:21].

Hence it was narrated from al-Fudayl ibn ‘Iyad (may Allah have mercy on him) that he said: “Whoever fears Allah, that fear will guide him to all that is good.” End quote. 

To sum up, Islam enjoins you to strike a balance between fear and hope and not let one of them outweigh the other. Rather you should travel with them towards Allah like a bird with two wings, and do not let the Shaytan have control over you so that your hope weakens, or let him make you forget the mutawatir evidence in the Quran and Sunnah that points to the vastness of Allah’s generosity. A small but sincere righteous deed may be sufficient to grant you admittance to Paradise. 

It was narrated from Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: “Whilst a man was walking on the road, he found a thorny branch on the road, so he removed it. Allah appreciated that and forgave him.” 

Narrated by Muslim, no. 1914.

See also the answer to question no. 125618

And Allah knows best.