Ibn al-Mubarak reported: Ja’far ibn Sulaiman, may Allah have mercy on him, said, “Concern about the world is a darkness in the heart, and concern about the Hereafter is a light in the heart.”
Source: al-Zuhd li-Ibn Abī Dunyā 543
عَنِ ابْنِ الْمُبَارَكِ عَنْ جَعْفَرِ بْنِ سُلَيْمَانَ رحمه الله قَالَ هَمُّ الدُّنْيَا ظُلْمَةٌ فِي الْقَلْبِ وَهَمُّ الآخِرَةِ نُورٌ فِي الْقَلْبِ
543 الزهد لابن أبي الدنيا