“This is a piece of advice that should be given to both the student of knowledge and other than the student of knowledge. This is because indulging in these things contradicts the guidance of the Prophet, as he used to forbid excessive luxury, and would sometimes enjoin others to be barefoot. The person who becomes accustomed to comfort will find it difficult to face various situations, as he will face things that do not correspond to the luxury and comfort that he is used to.
Let us take an example, and it is the example we mentioned of the hadith enjoining occasionally being barefoot. Some of the people do not leave their feet bare at times. They always have to have socks, khuffs, or shoes, and you never find them walking much. Such a man, were you to suggest to him that he walk 500 meters without anything protecting his feet, you would find this to be extremely hard on him. His feet might even start bleeding from the harshness of the ground! However, if he makes himself accustomed to harsh conditions and avoids constant comfort, you would find that he would be blessed with much good.
If the body is not accustomed to such conditions, it will not have immunity to pain. So, you would find such a person feeling pain from anything, while if he possessed immunity, he would pay it no mind. This is why you find the hands of laborers to be much stronger and firmer than the hands of students of knowledge. There is nothing to deter or prevent a laborer from doing anything since his hands have become accustomed to these conditions. This is to the point that if you touch the hands of a laborer, it is as if you are touching a rock because of the roughness and harshness, and if he were to wrap his fingers around your hand, it would hurt a lot. This is due to his long hours handling mud and bricks, and because he has accustomed himself to this.
So, when a person accustoms himself to comfort and luxury, there is no doubt that this will harm him greatly…”
[‘Sharh Hilyat Talib al-‘Ilm’; p. 43]