Allah, all praises and glory be to Him, has ordered:
“O you who believe! Eat of the lawful things that We have provided you with, and be grateful to Allah, if it is indeed He Whom you worship.” (Surah Al-Baqarah:172)
Apart from abstinence from food, drink and all that invalidates the fast during the days of Ramadan, the fasting of the stomach also includes the avoidance of prohibited things after the fast.
The believer does not deal in things such as interest or riba, because they will earn the wrath of their Lord the Most High. Allah tells us:
“O you who believe! Eat not Riba doubled and multiplied, but fear Allah that you may be successful.” (Surah Ali-Imran:130)
Those who eat from the proceeds of interest are actually fooling themselves. By filling their stomachs with unlawful gain, they are effectively closing the door to the acceptance of their prayers. As we saw in the discussion of hadith number 10, even the one in great need, who spreads his hand to ask his Lord, will have his request rejected if his sustenance is unlawful:
“…Then he [the Prophet peace be upon him] mentioned a man who after a long journey is disheveled and dust coloured. “[The man] stretches his hands out toward the sky and says, ‘O Lord, O Lord,’ while his food is unlawful, his drink is unlawful, his clothing unlawful and his nourishment is unlawful. How is he to be answered [in such a state]?” (Recorded in Sahih Muslim)
How can the stomach be considered to be fasting when it eats from unlawful food gained from unlawful wealth? Islam commands the seeking and earning of sustenance by lawful means. Any body that is nourished by unlawful food will find its destiny in the fire of hell.
Many people today eat as they like without considering deeply the origins of their food or its ingredients. This results in a hardening of the heart, and an inability to taste the sweetness of worship. We should therefore guard strictly what enters our mouths in order to facilitate our entry to Paradise.