Ad-Din means the reckoning, the reward or punishment. Similarly, Allah said,
[يَوْمَئِذٍ يُوَفِّيهِمُ اللَّهُ دِينَهُمُ الْحَقَّ](On that Day Allah will pay them the (Dinahum) recompense (of their deeds) in full) (24:25), and,
[أَءِنَّا لَمَدِينُونَ](Shall we indeed (be raised up) to receive reward or punishment (according to our deeds)) (37:53). A Hadith stated,
«الْكَيِّسُ مَنْ دَانَ نَفْسَهُ وَعَمِلَ لِمَا بَعْدَ الْمَوتِ»(The wise person is he who reckons himself and works for (his life) after death.) meaning, he holds himself accountable. Also, `Umar said, "Hold yourself accountable before you are held accountable, weigh yourselves before you are weighed, and be prepared for the biggest gathering before He Whose knowledge encompasses your deeds,
[يَوْمَئِذٍ تُعْرَضُونَ لاَ تَخْفَى مِنكُمْ خَافِيَةٌ ](That Day shall you be brought to Judgement, not a secret of yours will be hidden) (69:18).''
[إِيَّاكَ نَعْبُدُ وَإِيَّاكَ نَسْتَعِينُ ](5. You we worship, and You we ask for help.) (1:5)