What he had just seen while leading them
He climbed the pulpit straight after the prayer.
قَدْ أُرِيتُ الآنَ ـ مُنْذُ صَلَّيْتُ لَكُمُ الصَّلاَةَ ـ الْجَنَّةَ وَالنَّارَ مُمَثَّلَتَيْنِ فِي قُبُلِ هَذَا الْجِدَارِ، فَلَمْ أَرَ كَالْيَوْمِ فِي الْخَيْرِ وَالشَّرِّ
Qad urītu-l-āna, mundhu ṣallaytu lakumu-ṣ-ṣalāh, al-jannata wa-n-nāra mumaththalatayni fī qubuli hādha-l-jidār. Fa-lam ara ka-l-yawmi fi-l-khayri wa-sh-sharr
“I have just been shown, since I led you in the prayer, the Garden and the Fire, pictured in front of this wall. I have never seen good and evil as I saw them today.”
Where this comes from
Anas says he pointed with his hand towards the prayer direction of the mosque as he said it, and repeated the last sentence.
The full narration
Narrated Anas bin Malik:Once Allah's Messenger (ﷺ) led us in prayer and then (after finishing it) ascended the pulpit and pointed with his hand towards the Qibla of the mosque and said, "While I was leading you in prayer, both Paradise and Hell were displayed in front of me in the direction of this wall. I had never seen a better thing (than Paradise) and a worse thing (than Hell) as I have seen today, I had never seen a better thing and a worse thing as I have seen today
Source
Ṣaḥīḥ al-Bukhārī · 6468
- Agreed upon as authentic (al-Bukhārī / Muslim)