Ibn Al-Mubarak reported: Hasan Al-Basri, may Allah have mercy on him, said, “Verily, the believer is a guardian over himself and he holds himself accountable to Allah the Exalted. Verily, the reckoning will only be lightened on the Day of Resurrection for people who held themselves accountable in this world. Verily, the reckoning will only be grueling on the Day of Resurrection for people who did not hold themselves accountable.”

Source: As-Zuhd war Raqa’iq 307

عن ابن المبارك عَنِ الْحَسَنِ رحمه الله قَالَ إِنَّ الْمُؤْمِنَ قَوَّامٌ عَلَى نَفْسِهِ يُحَاسِبُ نَفْسَهُ لِلَّهِ عَزَّ وَجَلَّ وَإِنَّمَا خَفَّ الْحِسَابُ يَوْمَ الْقِيَامَةِ عَلَى قَوْمٍ حَاسَبُوا أَنْفُسَهُمْ فِي الدُّنْيَا وَإِنَّمَا شَقَّ الْحِسَابُ يَوْمَ الْقِيَامَةِ عَلَى قَوْمٍ أَخَذُوا هَذَا الأمْرَ مِنْ غَيْرِ مُحَاسَبَةٍ

307 الزهد والرقائق لابن المبارك