His full name is Abu Abdullah Harith bin Asad al-Basri. Muhasibi means self-inspection/audit. It was his characteristic property.
In al-Khalwa, in a discourse on fear and hope:
Know that the first thing that corrects you and helps you correct others is renouncing this world. For if you think of this world, you will not find it worth sacrificing your soul and faith for it. But you will find your soul worthier of honour by ridiculing this world.
This world is abhorred of God almighty and the messengers. It is an abode of afflication and a station of foolishness. Be on your guard from it.
Al-Khalwa's argument elsewhere cites al-Hasan al-Basri. The above pericope was later transplanted into a fictional response by al-Hasan to 'Umar b. 'Abd al-Aziz.