[Imam Muhammad b. ‘Ali] al-Baqir (as) has said: “There is no servant who sees his Muslim brother in need, however does not help him or tries to alleviate his difficulties, except that he will face a tribulation in that his energies will be expended in an area in which there is no reward for the next life and no reward for the transient world.
There is not a single servant (of Allah) who is miserly in spending his wealth in that which pleases Allah except that his wealth will end up being spent in the forbidden and prohibited channels where in lies Allah's anger.”[1]
Both the acts of obedience and sinning against Allah (SwT) have two effects to them:
1. Effects within the physical world;
2. Effects within the spiritual world.
Taking interest (from the banks or other institutions) has a spiritual effect which is the punishment on the Day of Resurrection and the squeezing in the grave; as for the effects in the physical world, the person who takes interest will be accursed and hated by others!
The effects within the physical world are broken up into two categories:
1. Some of them have a logical reasoning which we can understand with logical proofs. For example, we read in the Qur’an that:

وَ لاَ تَنَازَعُوا فَتَفْشَلُوا وَ تَذْهَبُ رِيـحَكُمْ

“…and do not quarrel with one another for then you will be weak, and your power will depart…”[2]
Thus, the effects in the physical world include arguments and differences amongst the people. We are able to understand the logic of this outcome since when there is an argument between people, naturally their power is dissipated. Instead of fighting the enemy, one would end up fighting with those of the same faith and close to the person!
In addition, the Qur`an also tells us (as another example of this phenomena):

إِدْفَعْ بِالَّتِي هِيَ أَحْسَنُ فَإِذَا الَّذِي بَيْنَكَ وَ بَيْنَهُ عَدَاوَةٌ كَــأَنَّهُ وَلِيُّ حَمِيمٌ

“…repel (evil) with what is best. [If you do so,] behold, between you and the person for which there was enmity will be as though he were a sympathetic friend.”[3]
Therefore, we must respond in a nice way to one who says something bad as this goodness would lead to the stubborn enemy having a change of heart and inclining such that he would become a close, loving friend! The A`immah (as) and the Noble Prophet (S) were the embodiment of this verse and it is through their love that they were able to humble the enemies.
2. Another effect in the physical world is a relationship which, although may not be exactly clear to us and which we cannot understand, nonetheless does exist. For example, it is mentioned in the traditions that:

 

صِلَّةُ الرَحْمِ تُعْمَرُ الدَيَّارَ وَ تَزِيدُ فِي الأَعْمَارِ

“Silatul Rahm (the act of the keeping the family bonds strong) enable the cities to be fortified and increases the life span.”
This is another physical act related to the world, however it is not clear how the life span increases through maintaining family ties.
In addition we read in the Qur`an:

وَ مَنْ يَـتَّقِ اللٌّهَ يَجْعَلْ لَهُ مَخْرَجاً وَ يَرْزُقْهُ مِنْ حَيْثُ لاَ يَحْتَسِبُ

“…and whoever is careful of (his duty to) Allah, He will make for him a means out (of his difficulties) and will grant him sustenance from where he imagines not (that it would come)…”[4]
What is the relationship between Taqwa of Allah (SwT) and sustenance coming from places where one cannot even imagine? Truly, this is something we cannot understand!
It is important to keep in mind that all types of worship and acts of transgression carry these forms of effects with them.
It is possible that after committing a sin, a person would repent and Allah (SwT) would accept his forgiveness, however the effect of that sin remains with the person in the physical world. Thus, the repentance for a sin merely takes away the effect of the act in the spiritual realm, however its spiritual effects remain for a time period. This is similar to poison which enters into a person's body and is not immediately taken out of the body forcing the person to ingest an antibody so that the effects of the poison do not stay with the person.
In the tradition quoted, we see that it refers to two effects of one's actions in the physical realm. If the society were to pay attention to these effects, then they would definitely correct themselves much quicker than the current pace of reformation.
We pray that Allah (SwT) grants all of us the opportunity to be able to pay close attention to the various educational programs and injunctions that Islam has blessed us with!

Notes:
[1] Tuhafatul Uqul under the short sayings of the 5th Imam and also Bihar al-Anwar, vol. 75, pg. 173
[2] Surat al-Anfal (8), verse 46
[3] Surat al-Fussilat (41), verse 34
[4] Surat al-talaq (65), verses 2 and 3