And those who give charity with their hearts trembling at the thought that unto their Sustainer they must return. Quran 23:60
In a hadith narrated by Aisha it is related she asked the Prophet if this verse was a reference to those who get intoxicated and practice thievery.
The Prophet answered: "No, O daughter of As-Siddiq. They are those who fast, perform Salat, give charity while they fear that their Lord will not accept it from them: “it is they who race to do good deeds, always taking the lead.” Referring to Quran 23:61
Tirmidhi: Book 47, Hadith 227
This Hadith illustrates how believers process characteristics of Fear and Humility. When they look at the humility and insignificance of their existence and then at the majesty of the Almighty, they feel overwhelmed and fear that their works will not help them in the Hereafter. The Prophet explained that Allah comforts the believers by attributing these characteristics to His closest servants.
Adapted from "A Sufi Study of Hadith" by Maulana Ashraf Ali Thanawi. Translated by Shaykh Yusuf Talal Delorenzo