Al-Ghazali reported: Abdullah ibn al-Mubarak, may Allah have mercy on him, said to Sahl ibn ‘Ali as he was in silent contemplation, “Where have you gone?” Sahl said, “The Bridge over the Hellfire.”
Source: Iḥyā’ Ulūm al-Dīn 4/425
عن الغزالي قال قَالَ عَبْدُ اللهِ بْنُ الْمُبَارَكِ رَحِمَهُ اللَّهُ يَوْمًا لِسَهْلِ بْنِ عَلِيِّ وَرَآهُ سَاكِتًا مَتَفَكِّرًا أَيْنَ بَلَغْتَ قَالَ الصِّرَاط
4/425 إحياء علوم الدين