خَيْرُ النَّاسِ قَرْنِي، ثُمَّ الَّذِينَ يَلُونَهُمْ، ثُمَّ الَّذِينَ يَلُونَهُمْ، ثُمَّ يَجِيءُ قَوْمٌ تَسْبِقُ شَهَادَةُ أَحَدِهِمْ يَمِينَهُ، وَيَمِينُهُ شَهَادَتَهُ
Translation: The best people are those of my generation, then those who follow them, then those who follow them. Later people will appear whose testimony races ahead of their oaths and whose oaths race ahead of their testimony.
Source: البخاري ومسلم
خَيْرُ النَّاسِ means “the best people”; قَرْنِي refers to the Prophet’s generation; and ثُمَّ الَّذِينَ يَلُونَهُمْ means “then those who follow them.” ثُمَّ expresses sequence.
The earlier generations occupy a special place in learning the religion and its first transmission. The second part warns about careless testimony and oaths, reminding students that claims must be backed by honesty.