«فَإِنْ سُمِّيَ الرَّاوِي، وَانْفَرَدَ رَاوٍ وَاحِدٌ بِالرِّوَايَةِ عَنْهُ، فَهُوَ مَجْهُولُ الْعَيْنِ»
If a narrator is named and only one transmitter reports from him, he is classed as majhūl al-ʿayn.
This is the basic formulation, subject to the subsequent qualification concerning trustworthy authentication. The person’s name may be present, yet the kind of biographical establishment required for evaluating a hadith is still lacking.
For example, a chain might explicitly name “Khālid ibn Zayd,” while available evidence identifies only one pupil and provides no sufficient independent evaluation. Naming someone does not establish his integrity. A later trustworthy biographical attestation may change the assessment, so the formula should not be read as an irreversible verdict.