Anas reported the Prophet (ﷺ) as saying, "O people, weep, but if you are unable to do so, then pretend to weep, for the inhabitants of hell will weep in hell till their tears flow on their faces as though they were streams, and when the tears stop blood will flow and the eyes will be made sore. If ships were blown along in them, they could sail." It is transmitted in Sharh as-sunna.
Source: sunnah.com
Other translations
Arabic
وَعَنْ أَنَسٍ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «يَا أَيُّهَا النَّاسُ ابْكُوا فَإِنْ لَمْ تَسْتَطِيعُوا فَتَبَاكَوْا فَإِنَّ أَهْلَ النَّارِ يَبْكُونَ فِي النَّارِ حَتَّى تَسِيلَ دُمُوعُهُمْ فِي وُجُوهِهِمْ كَأَنَّهَا جَدَاوِلُ حَتَّى تَنْقَطِعَ الدُّمُوعُ فَتَسِيلَ الدِّمَاءُ فَتَقَرَّحَ الْعُيُونُ فَلَوْ أَنَّ سُفُنًا أُزْجِيَتْ فِيهَا لجَرَتْ» . رَوَاهُ فِي «شرح السّنة»
sunnah.com