Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
quran:48:12

But you thought that the Messenger and the believers would never return to their families, ever, and that was made pleasing in your hearts. And you assumed an assumption of evil and became a people ruined."  

Nay (bal in both instances marks a transition from one subject to another), but you thought that the Messenger and the believers would never return to their families, and that ˹thought˺ was adorned in your hearts, that is to say, ˹you thought˺ that they would be annihilated by being slain and would not return, and you thought evil thoughts, that ˹just mentioned˺, and other things, and you were a ruined lot’ (būr is the plural of bā’ir), in other words, ˹a lot to be˺ destroyed according to God for ˹having entertained˺ such ˹evil˺ thoughts.
القرآن:٤٨:١٢

بَلْ ظَنَنْتُمْ أَنْ لَنْ يَنْقَلِبَ الرَّسُولُ وَالْمُؤْمِنُونَ إِلَىٰ أَهْلِيهِمْ أَبَدًا وَزُيِّنَ ذَٰلِكَ فِي قُلُوبِكُمْ وَظَنَنْتُمْ ظَنَّ السَّوْءِ وَكُنْتُمْ قَوْمًا بُورًا  

{بل} في الموضوعين للانتقال من غرض إلى آخر {ظننتم أن لن ينقلب الرسول والمؤمنون إلى أهليهم أبدا وزُيِّن ذلك في قلوبكم} أي أنهم يستأصلون بالقتل فلا يرجعون {وظننتم ظن السَّوء} هذا وغيره {وكنتم قوما بورا} جمع بائر، أي هالكين عند الله بهذا الظن.