Word by Word Analysis

وَيَوْمَ يَحْشُرُهُمْ كَأَن لَّمْ يَلْبَثُوٓا۟ إِلَّا سَاعَةً مِّنَ ٱلنَّهَارِ يَتَعَارَفُونَ بَيْنَهُمْ ۚ قَدْ خَسِرَ ٱلَّذِينَ كَذَّبُوا۟ بِلِقَآءِ ٱللَّهِ وَمَا كَانُوا۟ مُهْتَدِينَ 45

And on the Day when He will gather them, [it will be] as if they had not remained [in the world] but an hour of the day, [and] they will know each other. Those will have lost who denied the meeting with Allāh and were not guided.