Maulana Wahiduddin Khan I The Sunday Guardian I 22 June 2014

Promise means to commit oneself by a pledge to do or give something. Fulfilling a promise is the most positive and greatest quality of a person.

There is nothing comparable to it. According to the Islamic teaching, promise is not simply part of social ethics, it is a responsible pledge for which man is accountable before God.
The Quran says: "Keep your promises. You will be called to account [before God] for every promise which you have made." (17:34).

In another verse the Quran says: "O you who believe! why do you say that which you do not do? Grievously odious is it in the sight of God that you say that which you do not." (61:3)
To not fulfil a promise is a very wrong habit. It bears serious consequences for a man. To break a promise may ruin the whole personality of a human being. This habit and spirituality cannot coexist.

If one makes promises and fails to fulfil them, then this habit may lead to nonexistence of all positive qualities.

In social life a person possessing this habit loses his credibility. He will not be regarded as having a predictable character, which is the greatest social value of a person. Keeping promises is one's social identity. A person who loses this social identity will lose his social status.

The greatest danger of this habit is that such a person will be presented before God on the Day of Judgement and will be asked by Him: "Why did you fail to fulfil the promise after having pledged it?" It means that this habit has grave consequences, because a person of this kind takes the risk of being disgraced in the eyes of God.
Without doubt there is no loss greater than this.