Incidents people experience ever since their childhood affect the way their personalities develop in many ways. Sometimes difficulties and hardship, sometimes illnesses, deaths, sometimes the increase in the blessings they are given and the accomplishments they attained would cause people to maturate. Such a change in personality which continuously causes improvement in time and the incidents faced are beautiful blessings for man.
However, there are also "deviations in personality" that occur in people who do not have sound and stable personalities. But in these deviations, there is no constant improvement towards the better. The basic characteristic of such deviations is the "constant swings in the personality".
Big or small, ordinary or important, any kind of event in his life might be effective in causing changes in the personality of such a person. Sometimes a rainy, dark, gloomy, snowy or sunny day; sometimes not having slept sufficiently or not having eaten the preferred food; sometimes an emotional film watched on television might cause a change in such a person's character for that day. In the same manner an incident he experiences in his workplace or a situation which he might call to be a slip-up might cause him to assume a completely different personality. He might get all cheered up suddenly with one reason and get all saddened with another; and he might remain under the influence of these feelings for days or weeks.
It would not be possible to know according to what and when his personality would change. While someone who knows him for years would expect him to be the person he always knew; he would feel as if he is someone he doesn't know at all. That person, who generally responds to a joke in joy and modesty, might someday respond to such jokes in touchiness and unkindness. Or that person, who always helped everyone selflessly when asked for help, might someday react unwillingly and in discontent upon such a request. Someone who is always very fast, hard working and responsible might one day assume an uninterested, indifferent and irresponsible attitude. In short his one day does not match the other; one hour does not match the other. Since it is not possible to foresee these changes, people who establish friendships with such people, would come across surprise personalities.
This inconsistent personality model such people assume is highly disturbing. That is because one of the most important characteristics of a reliable, trustworthy person is the stability of his personality. And that can only be possible with that person being faithful. A person with a sound character, no matter which kind of hardships or blessings he faces, would never make concessions from the qualities of his personality under any circumstance. If such people are loyal, they always act loyal. If they are self-sacrificing, they always act selflessly. If they are reliable they always act reliable. Neither the weather conditions, nor the seasonal changes, nor the accomplishments they attain, or the hardships faced would ever affect such people's states of mind for that day. That is because Muslims shape their personalities according to the Qur'an. And since they aim to live the morality of the Qur'an in the most perfect manner every moment of the day, they do not change their morality by the day or hour.
The standard people should assume about this matter is to think about this: would they like to be close friends or companions of a person whose personality constantly changes, whose one day is not like the other, who can display a surprise attitude by the day, by the hour? Of course no one would want to be facing such a situation. Everyone would want to find someone he can trust, he can be sure that he knows. Everyone would want to know when his friend will do what, how he will react to what.
For that reason, taking this fact into consideration, everyone should enforce his personality in this way and aim to become a reliable person.
Muslims should never accept to live in such a changing personality as seen in the people of ignorant societies. If a believer is a good, indulgent, compassionate, conversable, easy going, hardworking, mature person he should be –at least- like this all the time. And in time, he should constantly improve himself and aim to become a better person.
That is the kind of morality most compliant to the approval of Allah. In the Qur'an Allah informed us that "right actions which are lasting are better in the Sight of Allah" as follows:
Wealth and sons are the embellishment of the life of this world. But, in your Lord’s Sight, right actions which are lasting bring a better reward and are a better basis for hope.(Surat Al-Kahf: 46)