if the stomach is ill, the veins return with disease
"As our Beloved Rasūl صَلَّى اللهُ تَعَالٰى عَلَيْهِ وَاٰلِهٖ وَسَلَّم has rightly stated, ‘The stomach is like a pond in the body and the veins are the streams which proceed towards this pond. If the stomach is healthy, the veins return with health and if the stomach is ill, the veins return with disease.’ (Shu’ab-ul-Īmān, vol. 5, pp. 66, Ḥadīš 5796) "