Reason behind revealing This Ayah, and the prohibition of Betrayal

The Two Sahihs mention the story of Hatib bin Abi Balta`ah. In the year of the victory of Makkah he wrote to the Quraysh alerting them that the Messenger of Allah ﷺ intended to march towards them. Allah informed His Messenger of this, and he sent a Companion to retrieve the letter that Hatib sent, and then he summoned him. He admitted to what he did. `Umar bin Al-Khattab stood up and said, "O Allah's Messenger! Should I cut off his head, for he has betrayed Allah, His Messenger and the believers" The Prophet said,

«دَعْهُ فَإِنَّهُ قَدْ شَهِدَ بَدْرًا، وَمَا يُدْرِيكَ لَعَلَّ اللهَ اطَّلَعَ عَلَى أَهْلِ بَدْرٍ فَقَالَ: اعْمَلُوا مَا شِئْتُمْ فَقَدْ غَفَرْتُ لَكُم»

In the third verse (27), Muslims have been instructed not to commit any breach of trust خِیَانہ (khiyanah) in the dual rights due against them, that is, in the rights of Allah (Huququllah) or in the mutual rights of the servants of Allah as enjoined on each other (Huququl-` Ibad) - either by failing to fulfill them totally, or by fulfilling them in a defective manner leaving one or the other shortcoming behind. Then, by saying: وَأَنتُمْ تَعْلَمُونَ (while you know) at the end of the verse, it was stressed that they already knew that breach of trust was an evil conduct lined with many a curse, therefore, going ahead to do something like that was not what an intelligent person would choose to do - and, since the cause of negligence or shortcoming in fulfilling the rights of the servants of Allah is usually one's attachment to property and children, a warning was given in verse 28 by saying: