عَنْ أَبِي الدَّرْدَاءِ رَضِيَ اللَّهُ عَنْهُ قَالَ بَيْنَمَا نَحْنُ عِنْدَ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ نَتَذَاكَرُ مَا يَكُونُ إِذْ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ إِذَا سَمِعْتُمْ بِجَبَلٍ زَالَ عَنْ مَكَانِهِ فَصَدِّقُوا وَإِذَا سَمِعْتُمْ بِرَجُلٍ تَغَيَّرَ عَنْ خُلُقِهِ فَلَا تُصَدِّقُوا بِهِ وَإِنَّهُ يَصِيرُ إِلَى مَا جُبِلَ عَلَيْهِ
It is narrated from Sayyiduna Abu Darda’ (may Allah be pleased with him), he says: We were discussing future events in the presence of the Messenger of Allah (peace and blessings be upon him) when he said: When you hear that a mountain has moved from its place, then verify it, but when you hear that a man's character has changed, do not verify this, because he will soon return to the character upon which his nature was created.