It is related that Maalik bin Deenaar (rahimahullaah) said:
Eating to the fill hardens the heart and weakens the body. [And he also said]: Whoever gains mastery over his stomach, will gain mastery over all the righteous actions.
Mawsoo'ah Ibn Abi al-Dunyaa (4/96) through Hayat al-Salaf of Ahmad al-Tayyar.
Note:. Eating to the fill is harmful to both health (sihhah) and faith (eemaan) and discipline in controlling one's appetite leads to discipline over all the righteous actions. If you can control the desires of the belly, then that training provides the patience required to master the (performance of) righteous deeds.
Translated by Abu Iyaad (@abuiyaadsp)