Allaah (The Most High) said:
وَاسْتَعِينُوا بِالصَّبْرِ وَالصَّلَاةِ ۚ وَإِنَّهَا لَكَبِيرَةٌ إِلَّا عَلَى الْخَاشِعِينَ
الَّذِينَ يَظُنُّونَ أَنَّهُم مُّلَاقُو رَبِّهِمْ وَأَنَّهُمْ إِلَيْهِ رَاجِعُونَ
And seek help in patience and As-Salat (the prayer) and truly it is extremely heavy and hard except for Al-Khashi’un [i.e. the true believers in Allah – those who obey Allah with full submission, fear much from His Punishment, and believe in His Promise (Paradise, etc.) and in His Warnings (Hell, etc.)]. (They are those) who are certain that they are going to meet their Lord, and that unto Him they are going to return. [2:45-46]
[الَّذِينَ يَظُنُّونَ أَنَّهُم مُّلَاقُو رَبِّهِمْ وَأَنَّهُمْ إِلَيْهِ رَاجِعُونَ- (They are those) who are certain that they are going to meet their Lord, and that unto Him they are going to return]: They are certain that they are going to meet their Lord in order to be recompensed for their deeds and that to Him is their return. This is what makes acts of worship easy for them, obligates solace on them during calamities, gives them relief in times of distress and turns them away from evil deeds (i.e. by the Tawfeeq of Allaah).
[Abridged and slightly paraphrased. Source: Tayseer al-Kareem Ar-Rahmaan Fee Tafseer Kalaam Al-Mannaan’ by Imaam Sadi (rahimahullaah). Publisher: Daar Ibn Hazm 1st Edition. 1424AH (Year 2003)]