Some persons from amongst my associates would turn to my Cistern; when I would see them and they would be presented to me, they would be detained in the way while coming to me. I would say: My Lord, they are my companions, they are my companions, and it would be said to me: You don't know what innovations they made after you. (Using translation from Muslim 2304a)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ لَيَرِدَنَّ عَلَيَّ الْحَوْضَ رِجَالٌ مِمَّنْ صَحِبَنِي وَرَآنِي حَتَّى إِذَا رُفِعُوا إِلَيَّ وَرَأَيْتُهُمْ اخْتُلِجُوا دُونِي فَلَأَقُولَنَّ رَبِّ أَصْحَابِي أَصْحَابِي فَيُقَالُ إِنَّكَ لَا تَدْرِي مَا أَحْدَثُوا بَعْدَكَ