Islam teaches that God is forgiving. Like with other religions, forgiveness requires repentance. Repentance basically means feeling bad about what you did wrong. Under Islam, the rule about forgiveness is basically: God forgives those who repent, so we should too.
Undoubtedly keeping promises and keeping one’s word are attributes of the believers, and breaking promises is one of the attributes of the hypocrites.
The believer who makes promises to people and breaks his promise may have an excuse or he may not. If he has an excuse then there is no sin on him, but if he does not have an excuse then he is a sinner.For example:
A – Forgetting
Allaah has forgiven us for forgetfulness whereby obligatory actions are omitted or haraam actions are committed. Allaah says (interpretation of the meaning):
“Our Lord! Punish us not if we forget or fall into error”
B – Being forced to break one’s promise.
Being forced is one of the impediments that make it permissible for a Muslim to break his promise, such as one who is detained or is prevented from fulfilling his promise, or who is threatened with a painful punishment.
C – A promise to do something haraam or not to do something obligatory.
Whoever promises someone that he will do something haraam for him, or that he will not do something that is obligatory, it is not permissible for him to fulfil that promise.
D – If something unforeseen happens to the one who made the promise, such as sickness, the death of a relative or breakdown of his means of transportation, etc.
There are many excuses, which all come under the heading of the verse (interpretation of the meaning):
“Allaah burdens not a person beyond his scope”
And Allaah knows best.