What is "La'agei Safah"?
Rashi: Every expression of La'agim, and "u'Leshon Ilegim" (32:4) are reversed speech; it is not straight to hear.
Who speaks unclearly to the nation?
Rashi: Anyone who speaks to them Nevu'ah or rebuke, it seems to them that he speaks unclearly, that they cannot hear him.
Radak: A Navi who speaks to them, it seems that he speaks unclearly, like one who stammers, so people cannot understand his words well, or he speaks another language. They cause that they not understand him.
Malbim: One who speaks another language, even if he is expert to speak in clear expressions, and similarly one who stammers, even though he speaks his nation's language, it is hard to understand him. All the more so if he [stammers and] speaks another language, and also does not know to speak in clear expressions! So seemed to them the Navi who speaks in Leshon ha'Kodesh with the ultimate clarity.
