Ibn Majah

Commentary:
(1)
Goodness is a habit; this means that the straight path is innate to human nature. A person possessing sound natural disposition (fitrah salim) does not feel any difficulty in walking the path of goodness. However, due to a corrupt environment or the whisperings and deceit of Satan, sometimes a person may tread the path of evil. Despite this, his conscience continues to shake him. Thus, whenever a person leaves a sinful life and turns towards goodness, he attains such a state of spiritual joy and inner satisfaction that he could not find in the seemingly beautiful life of sin. The teachings of Islam are in accordance with this sound natural disposition, as Allah the Exalted has said:
﴿فَأَقِم وَجهَكَ لِلدّينِ حَنيفًا فِطرَ‌تَ اللَّهِ الَّتى فَطَرَ‌ النّاسَ عَلَيها لا تَبديلَ لِخَلقِ اللَّهِ ذلِكَ الدّينُ القَيِّمُ﴾ (al-Rum: 30)
That is, “The law and religion of Allah is that upon which He has created people; there is no change in the creation of Allah. That is the upright religion.”

(2)
Sin is a conflict.
This means that the one who commits a sin feels an inner struggle. The commanding self (nafs ammara) invites him towards sin and prevents him from repentance, while the conscience tries to restrain him from sin. This is why, although the one committing the sin outwardly does what he desires, he still does not attain happiness. The wealth of the world is unable to provide him with peace of heart, except if his conscience becomes completely dead and his nature is utterly corrupted.