All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
It is not permissible for those attending the Friday Khutbah to read a book during the Khutbah, because this consists in being distracted from listening to the Khutbah, and listening to it is obligatory according to the majority of the scholars.
Ibn Rushd said in Bidaayat Al-Mujtahid: “The scholars have three different opinions on listening silently on Friday while the Imaam is delivering the Khutbah: some of them are of the view that listening is obligatory in all cases and that this is a binding ruling among the rulings of the Khutbah. This is the view of the majority of the scholars including Maalik, Ash-Shaafi‘i, Abu Haneefah and Ahmad ibn Hanbal as well as the view of all the renowned jurists around the (early) Islamic world (Fuqahaa' Al-Amsaar).” [End of quote]
The fact that he does not understand the Arabic language is not an excuse for not listening, and he could distract those who understand it when they see him reading a book. Indeed, the scholars said it is obligatory not to be preoccupied with anything other than the Khutbah even for those who do not hear it. Abu Al-Waleed Al-Baaji said in Al-Muntaqa: “Listening silently to the Khutbah is obligatory on those who attend it whether they can hear it or not; Maalik, Abu Haneefah and most of the scholars stated this.” [End of quote]
What you and that person did is evidence for this. Because of him reading a book, that person spoke to you and asked you to tell him to listen, and you spoke to him and told him to listen. If this occurred from all of you during the Khutbah, then all of you have committed what is forbidden. Abu Hurayrah narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said: “If you say "Listen silently" to your companion on Friday when the Imaam is delivering the sermon then you have engaged in idle talk.” [Al-Bukhari and Muslim]
Allaah Knows best.