إِنَّهُ سَيَكُونُ فِي آخِرِ هَذِهِ الْأُمَّةِ قَوْمٌ، لَهُمْ مِثْلُ أَجْرِ أَوَّلِهِمْ، يَأْمُرُونَ بِالْمَعْرُوفِ، وَيَنْهَوْنَ عَنِ الْمُنْكَرِ، وَيُقَاتِلُونَ أَهْلَ الْفِتَنِ
Translation: In the latter part of this community there will be people with a reward like that of its earliest members: they will enjoin good, forbid wrong, and confront those who spread turmoil.
Source: البيهقي في دلائل النبوة
فِي آخِرِ هَذِهِ الْأُمَّةِ points to a later period. لَهُمْ مِثْلُ أَجْرِ أَوَّلِهِمْ describes a reward connected with righteous perseverance.
يَأْمُرُونَ بِالْمَعْرُوفِ means enjoining recognized good, and وَيَنْهَوْنَ عَنِ الْمُنْكَرِ means discouraging wrong. Responsible correction needs sound knowledge, appropriate authority, tact, and awareness of consequences.