The Salaf worked diligently in perfecting their actions and making them faultless, then after that, they showed great concern for acceptance of their actions. They did this because they feared that their actions would be rejected. They are those who gave what was incumbent upon them while their hearts were in a state of fear. It is reported that ‘Ali bin Abi Talib (radiallaahu ‘anhu) said:

Be more concerned that your actions are accepted than your concern of performing the action itself. Did you not hear the statement of Allaah:

Verily Allaah only accepts the actions of the Mutaqeen (pious).

Fudalah said: For me to know that Allaah has accepted from me an action the size of a mustard seed is more beloved to me than this world and everything within it. This is because of the statement of Allaah:

Verily Allaah only accepts the actions of the Mutaqeen (pious).

Malik bin Dinar said: Fear that an action is not accepted is more difficult than performing the action itself.

‘Ataa as Sulamee stated: The pious fear that their righteous actions were not done sincerely for Allaah.

‘Abdul ‘Azeez ibn Abee Ruwaad said: I have met people very diligent in performing actions, and upon completion of those actions they are faced with sadness in fear of the action being accepted or not.

The Salaf would supplicate 6 months to Allaah to allow them to reach the month of Ramadan, and then upon completion of the month, they would again supplicate 6 months (begging) for acceptance of their fast.

Some of the Salaf would display sadness on the day of ‘Eid. It was said to them: This is a day of happiness and joy! They would respond: You have spoken the truth, but I am a servant, my Lord has ordered me to perform an action but I am not sure if He will accept it from me or not.

Wahb noticed people laughing on the day of ‘Eid, upon seeing this he stated: If their fast was accepted, then know that this is not the action of those who are grateful, and if it was not accepted, then this is not the action of those who are afraid.

Hasan (al-Basree) stated: Indeed Allaah has made Ramadan a means of gain for His creation. (Within this month) they race to gain His pleasure through obedience to Him. Some individuals will gain (win), while others will remain back and lose. It is amazing to see a person playing and laughing on a day that the good doers will be rewarded, and the wrong doers will be defeated.

It is reported that Hasan al-Basree said:

The believer does the best deeds yet is most fearful [that his deeds will not be accepted]. If he were to spend a mountain of wealth [in charity], he would not feel sure [of the reward] until he sees it. The more righteous and pious he becomes, the more he fears.

But the hypocrite (munaafiq) says, ‘There are so many people, I will be forgiven, no problem.’ So he does wrong and evil deeds, yet holds foolish wishes about Allaah.

Source: Al-Dhahabee, Siyar A’laam Al-Nubalaa` 4:586, via Sayings of The Salaf.
May Allaah have mercy on all our Salafee scholars, and preserve the Deen of those still living.