All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.

Friday prayer is an individual duty on every free, sane, adult and resident Muslim man, who is able to go to perform it and having no excuses that allow him to leave it behind, according to the scholarly consensus. The Proof of this is that Allah the Almighty says {What means}:  

﴾"O you who believe (Muslims)! When the call is proclaimed for the Salât (prayer) in Friday (Jumu ̀ah prayer) come to the remembrance of Allah [Jumu ̀ah religious talk (khutba) and Salât (prayer)] and leave off business (and every other thing). That is better for you if you did but  know![Al-Jumu`a (Friday): 9]. It is the duty of the deaf and mute to attend the Friday prayer regardless of whether he understands the sermon or not and he is excused for not hearing the sermon. However, it is recommended that he keeps himself busy with remembering Allah and supplicating Him for this is more deserving than doing nothing. Please check the Shafie book {Boshra al-Kareem, P.402}.

In fact, there is no sin in keeping himself (the deaf and mute) busy with watching the sign language interpreted Friday sermon while at the mosque. By doing so, he is learning the rulings of Sharia, virtues and supplication. Rather, he is keeping track of the issue addressed by the Khateeb (One delivering the sermon) at the mosque where is sitting.

In conclusion, conducting the Friday sermon in sign language is a form of helping one another in goodness in addition to being of great benefit as it enables the deaf and mute to acquaint himself with the topic of the sermon including the rulings and admonitions. This enables this class of society to understand the sermon and gain religious knowledge as well as receive the full reward of attending the Friday prayer at the mosque. The proof of this is that The Messenger of Allah (Peace and blessings be upon him|) said: "Whoever washes (Ghassala) and performs Ghusl, comes early to the Masjid and sits near the Imam, and does not engage in idle talk, he will have for every step he takes (the reward of) a year's worth of good deeds, fasting it and praying Qiyam during it." {Related by An-Nasa`i}. And Allah the Almighty knows best.