Risālat al-Ḥuqūq
Hadith 9وَأَمَّا حَقُّ بَطْنِكَ فَأَنْ لا تَجْعَلَهُ وِعَاءً لِلْحَرَامِ وَلا تَزيد على الشَّبْعَ.
The right of your stomach is that you make it not into a container for that which is unlawful to you and you eat no more after you become full.