Replying to the Salaam of a disobedient Muslim
22-11-2009 | IslamWeb
Question:
as salaamu alaykum dear respected scholars. My question deals with the precious phrase 'As salaamu Alaykum' and the response. is it a must to return this precious phrase in heaven to those who fight you for your faith and only use this precious phrase as a ruse to catch you off guard to their real intentions of working against you and the mu'mineen. When I feel obligated to return salaam to them, I feel not good since I am returning these precious words of Jinnah to my enemy or ememies. this question has been talked about by many of my brothers from the masjid I worship in; and there has been many have given conflicting answers. those who are fighting me and my brothers for our faith aren't offering peace or wishing for our well being, after saying As salaamu alaykum! and when I respond in kind to these individuals, certainly how can I offer them peace when they have and currently committing treachery against me and my brothers in Islam. Jazakum Allahu Khayran
Answer:
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.
Saying Salaam is a Sunnah (recommended act), whereas replying to it is obligatory as previously clarified in Fatwa 90969. It is permissible for the Muslim to reply to the Salaam said to him by a non-Muslim, let alone a disobedient Muslim. Replying to the Salaam of a non-Muslim should be only with the word "Wa ‘Alaykum" (and upon you) no more. Some scholars held the opinion that replying to the non-Muslim’s Salaam may be with "Wa ‘Alaykum Assalaam" if the Muslim knew that he said Salaam in the same formula.
As regards replying to the Salaam of the disobedient Muslim, it should be with the same formula or a better one. Indeed, asking Allaah to grant him peace, mercy and blessing may be a cause for his safety from sins, and him entering by the mercy and blessing of Allaah among the believers by repenting to Allaah The Almighty.
It is permissible to desert a Muslim because of his misdeeds, as the Prophet, sallallaahu ‘alayhi wa sallam, deserted Ka‘b ibn Maalik and his two companions 
. Deserting a disobedient Muslim may include declining to reply to his Salaam until he quits his misdeed and announces his repentance. This should be done so long as deserting will not result in a considerable evil. Otherwise, it would be more appropriate not to desert him. For further information see Fatwa 84976.
Allaah Knows best.