Lonaphala Vagga. The tenth chapter of the Tīkā Nipāta of the Anguttara Nikāya. A.i.239-58.
Lonaphala Sutta. There are certain persons, careless in habits of body and thought, without insight even a small offence takes such persons to hell, while others expiate a similar small offence in this very life. A grain of salt cast into a small cup of water renders it undrinkable, but such is not the case if it be cast into a river. The same idea is illustrated with other similes. A.i.248ff.