لَمْ يَنْسُبِ الطُّلَّابُ إِلَى أَنْفُسِهِمْ مَا لَمْ يَرَوْهُ. وَالصِّدْقُ أَصْلُ الْعِلْمِ.
The students did not attribute unseen observations to themselves. Truthfulness is the foundation of knowledge.
The first is a particular report; the second articulates a general principle reinforcing its value. A self-contained, generalizing follow-up of this kind may function as tadhyīl when it confirms the prior meaning.
Al-ṣidqu aṣlu al-ʿilm is an independent predication, not a mere qualifier added within the initial sentence. That helps distinguish tadhyīl from tatmīm.