I believe that there is not one of us that has not made and is still making mistakes in life.
Some of us once we make a mistake become very  hard and refuse to console ourselves in the knowledge that we have a forgiving Lord, providing that we repent and promise not to repeat.
Forgiveness and repentance is  mentioned in a multitude of ayahs in the Noble Qurâan.
Allah says in the Noble Qurâan:
But if they cease, then Allah is Oft-forgiving, Most Merciful. (Al-Baqarah 2:192)
Except for those who repent after that and do righteous deeds. Verily, Allah is Oft-forgiving, Most Merciful. (Aale Imran 3:89)
So once we realise that we err, we must stop immediately, repent and try our very best not to repeat.
A believer should always be in the state between fear and hope.
For these there is hope that Allah will forgive them, and Allah is Ever Oft Pardoning, Oft-forgiving. (An-Nisa 4:99)
Fear as to not disobey Allah and His Commandments and Hope for the Forgiveness of the Most Merciful.
We must be well aware of the whispering of shaitan, who wants us far removed from our Lord. He will whisper... You have repeated your Mistake/Sin. No point in asking for forgiveness?
Now for a different scenario:
Some of us turn our attention to others and we become very critical and judgmental to their mistakes/sins, self assured of our own perfection, blind to our own shortfalls. Astagfirullah.
Oh! No, no, no, this is not the way to stand in prayer, No, no, and no!!! This is not how a good Muslim behaves...�, No, no, no, sister you are wearing your hijaab the wrong way!!! Do I need to continue? Of course if we see something in others that we are convinced is wrong we can approach the matter in a kind and gentle manner and give advice but with the purest of intentions. InShaAllah.
Let’s see how the Prophet (sallallahu alayhi WA Salam) dealt with the mistakes of others:
Narrated Abu Huraira: A Bedouin urinated in the mosque, and the people rushed to beat him. Allah's Apostle ordered them to leave him and pour a bucket or a tumbler (full) of water over the place where he has passed urine. The Prophet then said, “You have been sent to make things easy (for the people) and you have not been sent to make things difficult for them."  Bukhari (Book #73, Hadith #149)
Mistakes/sins can be made in ignorance or  in matters that we are well aware that we should not do.
The believer struggles day in and day out to correct himself/herself and lead a pious life.
The believer learns from his mistakes, refuses to keep on berating himself and does not say “ What if�..
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: A strong believer is better and is more lovable to Allah than a weak believer, and there is good in everyone, (but) cherish that which gives you benefit (in the Hereafter) and seek help from Allah and do not lose heart, and if anything (in the form of trouble) comes to you, don't say: If I had not done that, it would not have happened so and so, but say: Allah did that what He had ordained to do and your" if" opens the (gate) for the Satan. (Shahih Muslim- The Book of Destiny)
When a mistake happens due to ignorance or due to weakness, the believer remembers the words of His Lord:
Anas (radhiallahu anhu) said that he heard the Messenger of Allah (sallallahu alaihi wa-sallam) say: “Allah the Exalted said: “O son of Adam! As long as you invoke Me and plead to Me, I will forgive you whatever you have committed, and I will not make much of it. O son of Adam! If your evil deeds reach the borders of the sky, and then you ask Me for forgiveness, I will forgive you. O son of Adam! If you bring forth the earth full of errors, then you meet Me while you do not associate anything (or anyone) with Me, I will bring forth for you its full of forgiveness.  [At-Tirmidhee (Shaikh Albanee rendered it as Hasan)]
I just hope and wish that we all become a little more forgiving towards each other.
