To Hassan bin Uthman, some followers, when the imam rises from bowing, say as he says: "Sami' Allahu liman hamidah," and some say: "Rabbana wa laka al-hamd." Which one is more correct?

This is one of the issues where scholars differ, but the most apparent view is that when the follower hears the imam say "Sami' Allahu liman hamidah," he should say "Rabbana wa laka al-hamd."

Or he can say any of the reported phrases, such as: "Rabbana wa laka al-hamd, Rabbana laka al-hamd," or "Allahumma Rabbana laka al-hamd, Allahumma Rabbana wa laka al-hamd."

So there are four phrases he can say. But if he says with the imam "Sami' Allahu liman hamidah," then says "Sami' Allahu liman hamidah," and after that says "Rabbana wa laka al-hamd,"

or "Rabbana laka al-hamd" and the other phrases, then in this he has done something that some jurists have said.

However, the apparent view is what came in the hadith, the saying of the Prophet ﷺ: When he says "Sami' Allahu liman hamidah," then you should say "Rabbana wa laka al-hamd."

That is why we say this is the most apparent view, but some scholars follow a different opinion.

Among the narrations about this is that the imam is appointed to be followed, so he says the words that are to be followed, and then the follower says what has been mentioned in this regard from the words of Allah.