Is it permissible for a follower of a scholar to issue a ruling on a matter in which he is following that scholar, in the science of hadith, for example?

The questioner : Some ignorant people might memorize a phrase, for example, "So-and-so authenticated it, my brother, no..." So, is it said here: "It is not permissible for a follower of a scholar to issue a ruling on a matter in which he is following that scholar"? Is this a valid argument?

The Shaykh : Of course, it is said, whether... or...

The questioner: Yes.

The Shaykh : What do they define as haram, halal, authentic, and weak?

The questioner: Yes.