6. It hinders sleeping and keeps the person awake. Because the one who eats to his fill and drinks a lot of water sleeps for longer periods which causes loss of worship such as performing prayers at night.
It also causes stupidity, and hard-heartedness while age is the most precious jewel and the capital of the person with which he trades, and sleeping is but death, so if one sleeps for longer periods it means he is losing his age.
The merit of praying at night when the people are asleep is well understood, so when one sleeps he will lose such a merit. If he prays while he is drowsy he will not perfect his deed of worship. Sleep is the origin of evil, becoming satiated invites it, and hunger constrains it.
7. Hunger makes easy punctuality in worship while satisfaction of food prohibits it because it needs time to be spent in eating: buying, cooking and washing of utensils; then the need for water closet every now and then. The period spent in such actions are better to be spent in remembering, reciting Qur’an and other deeds of worship, because it is more beneficial.
As-Sirri said: ‘I saw some fine flour with ‘Ali al-Jirjani who was swallowing it.’ I said to him: “Why do you do that?” He said: “I counted the time consumed for both cooking and swallowing and found that it takes seventy “Subhan Allahs” glorifying Allah (I) seventy times, so I stopped baking bread since forty years.”
See how keen he was to make use of his time. Each breath of the age is a valuable pearl which has no price — in this world — so you should conserve it, for the Hereafter when it pays much to expend, by remembering Allah (I) and obeying Him (I).
One of the difficult things when a person eats much is keeping purity for longer times and staying in the mosque. Such a person needs to leave the mosque every now and then to drink water and also to urinate. Observing fasting is easier for the person who is used to be hungry.
Observing fasting and retiring into a mosque for prayer, always keeping purity and making use of time by worshipping instead of eating and fulfilling needs, is really something profitable, but ignored by those unaware of the value of religion who has become satisfied with the life of this world:
[They know only the outside appearance of the life of the world [i.e., the matters of their livelihood, like irrigating or sowing or reaping, etc.], and they are heedless of the Hereafter.] (Qur’an 30:7)
Abu Sulaiman Ad-Darani pointed out six adversities of getting satiated with much food, he said: Six adversities hit the sated person: Loss of taste of confidential talks, difficulty in gaining wisdom, obstruction from being kind to human beings. Because he is sated he will imagine that all people are sated too, feeling bored of devotional acts.
The most sincere Muslims are found around mosques while the sated people are rotating round waste containers.