SINCERE GRATITUTE AND REGRET!!! 
Willingness to accept responsibility for the harm we may have caused or express thankfulness for the benefits we may have received are signs of moral maturity
How uncommon has common courtesy become? "Thank you" and "I'm sorry" are amazingly powerful expressions that could convey authentic appreciation or genuine remorse. These are common phrases that are unfortunately becoming increasingly rare.
"If you give thanks , I will give you more (of My Blessings).'' (Quran 14:7)
The Messenger of Allah [peace be upon him] said :"He who does not thank people, does not thank Allah". ( Ahmad, Tirmidhi )
One of the most devastating realities has been the fact that people for whom you truly care and for whom you do the most are often the ones who turn out to be the most ungrateful. They suffer deliberate amnesia (forgetfulness) and, in the process, even deny their indebtedness. Those for whom you would stake your prized privileges are often the ones who later undermine your integrity for the sake of fame or material gain. Such are they who have no conscience.
Conscience is that internal compass that directs us towards sound moral judgement. It measures our attitudes and conduct in relation to our ethical principles. Conscience manifests its judgements with the reward of peace of mind for those who do what they should, and with the penalty of guilt for those who don't. If we consider ourselves good, and don't have the decency to do what we should, then we are not really as good as we think we are.
People of conscience are people of character and good character (akhlaaq) is in fact ethics in action. People of character have the emotional intelligence to realize their errors and to acknowledge their indebtedness to others and thus possess the moral courage to express genuine regret by saying "I'm sorry," or genuine appreciation by saying "Thank you".
Willingness to accept responsibility for the harm we may have caused or express thankfulness for the benefits we may have received are signs of moral maturity. Heartfelt apologies could lead to reconciliation and easing of tension while sincere expressions of gratitude are valued gifts to people who have privileged us. Absence of an appropriate thanks or an owed apology could be damaging.
Don't get it wrong, people do sometimes use "Thank you" and "I'm sorry" but merely as a hollow rule of custom. In one's absence they negate their thankfulness or regret in the company of others. Such "Thank you " and "Sorry" means absolutely nothing. We even teach our little kindergarten kids to say "Thank you" but too often it connotes only formalistic politeness without nurturing true feelings of gratitude. If we say "Thank you" without really feeling thankful or "Sorry" without experiencing real regret then these words merely serve as mindless rituals; just like a wrapped gift box without any gift inside.
It takes strength of ego and tremendous moral fortitude to comply with ethical standards of true accountability.
The arrogant and the morally bankrupt do not, therefore, express remorse or regret easily. Genuine apology arises out of a conscience that values ethical principles of respect and responsibility. The only kind of apology that truly merits forgiveness is the apology of those who sincerely acknowledge and accept personal accountability for their misconduct and genuinely regret the consequences of their wrongdoings. The Prophet [pbuh]is reported to have said: "Real regret (nadam) is the basis for true repentance."
The ethical dimension to gratitude demands genuine thankfulness proportionate to the blessings received, never to deny those blessings nor devalue the worth of those who so bless us.
The Messenger of Allah Muhammad [peace be upon him] said:"The Merciful One shows mercy to those who are themselves merciful (to others). So show mercy to whatever is on earth, then He who is in heaven will show mercy to you " ( Abu Dawud, Tirmidhi )
SINCERE GRATITUTE AND REGRET!!! 