Morality in Islam addresses every aspect of a Muslim's life, from greetings to international relations. It is universal in its scope and in its applicability. A Muslim is expected to not only be virtuous, but to also enjoin virtue. She/he must not only refrain from evil and vice, but must also actively engage in asking people to eschew them. In other words, they must not only be morally healthy, but must also contribute to the moral health of society as a whole.
But when you are greeted with a greeting [of peace], answer with an even better greeting, or [at least] with the like thereof. Verily, God keeps count indeed of all things. [Qur’an 4:86](Asad) (4:86)
ﺎﺣﺴِﻴﺒ ٍﺀﻲﻋﻠﹶﻰ ﹸﻛﻞﱢ ﺷ ﻛﹶﺎﻥﹶﺎ ﺇﹺ ﱠﻥ ﺍﻟﻠﹼﻪﻭﻫﺩ ﺭﺎ ﺃﹶﻭﻬﻨ ﻣﺴﻦ ﺣ ﻮﺍﹾ ﹺﺑﺄﹶﻴ ﹶﻓﺤﻴﺔﺘﺤﻢ ﺑﹺﺘﻴﻴﻭﺇﹺﺫﹶﺍ ﺣ http://www.whyislam.org/