It is narrated from Hasan al-Basri, may Allah have mercy on him, that he said: There is no respect between you and a transgressor.
Hadith Referenceالادب المفرد / كتاب السلام / 1018
Hadith Gradingالألبانی:صحيح
Hadith Takhrij«صحيح : تفرد به المصنف»
Explanation & Benefits
Shaykh Maulana Usman Muneeb
Benefits and Issues: The point is that greeting (salam) mutually indicates etiquette and respect. When a transgressor (fasiq) is not to be respected, then there is no need to greet him with salam either.
Source: Fadlullah al-Ahad: Urdu Commentary on al-Adab al-Mufrad, Page: 1018