What is the importance of honesty and keeping promises in Islam?

 Honesty:

Honesty is fundamental to building economic and social relationships there is a condition. In a society where integrity is lost, from business matters to relationships at home, irreparable damage is created everywhere. Confidence rises from each other. Islam exhorts honesty to protect those who take its name from all these harms. 

Allah Ta'ala has said in the Holy Qur'an:

Surah Al-Nisaa verse 58:

Translation: 

In fact, Allah commands you to entrust your trusts to those who trust you. 

Also, where other attributes of those who get the welfare of this world and the hereafter have been mentioned, this has also been said. 

Surah Al-Mu'minun verse 8:

Translation:

And those who guard their trusts and their covenants. 

Who does not know about the Holy Prophet Muhammad Mustafa (peace be upon him) that even before he ascended to the position of prophethood, he was called by the title of "Al-Amin", meaning the honest one, in the dishonest Arab society. It was a sign of the sense of honesty of Prophet Muhammad Mustafa (peace be upon him) that even when he migrated to Medina

Prophet Muhammad Mustafa (peace be upon him)  arranged the payment of the trusts of the people who wanted to kill him. Islam did not limit the concept of honesty to just commercial business, but expanded it to include the payment of all the rights of the servants in the realm of honesty. 

The Prophet Muhammad Mustafa (peace be upon him) , may God bless him and grant him peace, said about trust: "What is said in the meeting is fidelity".In other words, after hearing something in one place, going to another place and narrating it is also part of bad faith. Prophet Muhammad Mustafa (peace be upon him) went further than that he advised Muslims to consider all their physical and mental abilities as trusts given by Allah Almighty and use them all with the feeling that one day Allah Almighty will give an account of these trusts. In view of this definition of honesty, it is impossible for a person to be a Muslim and also to be dishonest. That is why the Holy Prophet Muhammad Mustafa  (peace be upon him) said:

He who does not have honesty doesn't have faith. 

Commitment:

Fulfilling a promise is very important in human relationships. Most of our affairs are based on promises. If the promises are fulfilled, then things are fine. If promises start being broken, everything goes awry. In order to keep Muslims safe from this corruption, Islam advises to take oath of allegiance. Allah Ta'ala has said about the fulfillment of the covenant:

Surah Al-Israa verse 34:

Translation:

And fulfill the promise, surely the promise will be asked. 

The most important of all man's promises is the one he made to his Creator in eternal servitude.

 The Holy Quran has reminded him in this way:

Allah Almighty says in the Holy Qur'an:

Surah Al-An'am verse 153:

Translation:

 And Allah has commanded you to fulfill the covenant. So that you take advice. 

At another place, it was instructed to respect mutual agreements and collective relations as follows:

Surat Ar-Ra'd verse 20, 21:

Translation:

Those who fulfill God's covenant and do not break their vows, and those whom God has ordered to keep couples, keep them together and fear their Lord and fear evil reckoning. 

The Prophet Muhammad  Mustafa (peace be upon him), peace and blessings of God be upon him, kept his covenant even in the most difficult situations. For example, when Hazrat Abu Jundal was chained on the occasion of Peace of Hudaybiyah he came to the service of the Prophet Muhammad Mustafa (peace be upon him)  and showed the scars on his body that the people of Makkah had tortured Hazrat Abu Jundal for becoming a Muslim, and requested that he be taken with him to Madinah. So the Prophet Muhammad Mustafa (peace be upon him) refused to take them with him to Madinah simply because an agreement had been made with Quraysh that the Muslims who had fled from Makkah would be returned from Madinah. The painful condition of Hazrat Abu Jandal was a cause of indecision for all the Companions, but in view of the custody of Hudaybiyyah, they all acted patiently. 

The Holy Prophet (PBUH) said:

Translation: He who does not fulfill his promise has no religion.

Our dealings and mutual rights are governed by this Agreement. Therefore, the requirement of religion is that we observe all of them.