Марьям 19:54

وَاذْكُرْ‌ فِي الْكِتَابِ إِسْمَاعِيلَ

"And mention in the Book (the story of) Isma` il." - 19:54.

The reference here is clearly to Sayyidna Ismail (علیہ السلام) the son of Sayyidna Ibrahim (علیہ السلام) ، who has not been mentioned earlier along with his father Ibrahim (علیہ السلام) and brother Ishaq (علیہ السلام) but mention has been made of him after a brief interlude in which an account of Sayyidna Musa (علیہ السلام) is given. It is possible that by making a reference to Sayyidna Ismail (علیہ السلام) apart from others, instead of treating him along with them, the intention was to give him prominent status. In this verse the prophets have not been mentioned in the order in which they were granted missions of prophethood, because Idris (علیہ السلام) who has been mentioned last was, in fact, the earliest of them all.

كَانَ صَادِقَ الْوَعْدِ

"He was indeed true to his promise." - 19:54.

Fulfillment of promise .is regarded as an important part of the moral code by all decent men, just as a breach of it is considered worthy of contempt. A saying of the Holy Prophet ﷺ has described the breaking of promise as a sign of hypocrisy. Thus, none of the prophets and messengers of Allah have been accused of bad faith / a breach of promise.

Here certain attributes have been assigned to some of the prophets, but this does not mean that the other prophets did not possess them. It only suggests that these special attributes distinguish them from all the other prophets, just as Sayyidna Musa (علیہ السلام) has been described as مُخلَص . All the other prophets possessed this quality, but it has been specifically applied to Sayyidna Musa (علیہ السلام) . Hence a special mention of him with the attribute.

Sayyidna Ismail (علیہ السلام) occupies a place of honour where keeping a promise is concerned and he stood by his promise whether made to Allah or to humans. He fulfilled his promise to Allah that he would offer himself for sacrifice and will not be found wanting in courage. When the time came he stood by his promise. Once, he promised to meet a man at an appointed place and time. The man did not turn up at the appointed time, but Sayyidna Ismail علیہ السلام waited for him at the place for three days, and according to another tradition for full one year. (Mazhari) A similar incident is reported about The Holy Prophet ﷺ by Tirmidhi on the authority of Abdullah Ibn Ari Al-Khamsa that he waited for three days for someone who had promised to meet him at a particular place. (Qurtubi)

Importance of keeping one's promise.

Fulfillment of promise is a distinctive trait of the character of the prophets and the pious, and a normal code of conduct with all decent persons. Breaking of a promise, on the other hand, is a habit of the wicked, mean and liars. A saying of The Holy Prophet ﷺ is اَلعدۃ دَین "A promise is like a debt." i.e. it is as obligatory to honour a promise as it is to repay a debt. There is another saying of The Holy Prophet ﷺ which says وای المؤمن واجب . It means that "promise is an obligation for a believer."

Jurists are all agreed that a promise is a debt and its fulfillment obligatory, but only in the sense that its violation without a religious (شرعِی) excuse is a sin though no remedy can be sought for its breach in a court of law. In the language of the Jurists a debt is an obligation which is enforceable, while a promise is not.