Narrated `Abdullah bin Mas`ud: We used to say the greeting, name and greet each other in the prayer. Allah's Apostle heard it and said:--"Say, 'at-tahiyyatu lil-lahi was-salawatu wat-taiyibatu . Assalamu 'Alaika aiyuha-n-Nabiyu warahmatu- l-lahi wa-barakatuhu. _ Assalamu alaina wa-'ala 'ibadi-l-lahi as-salihin.. Ashhadu an la ilaha illa-l-lah wa ashhadu anna Muhammadan `Abdu hu wa Rasuluh. (All the compliments are for Allah and all the prayers and all the good things (are for Allah). Peace be on you, O Prophet, and Allah's mercy and blessings (are on you). And peace be on us and on the good (pious) worshipers of Allah. I testify that none has the right to be worshipped but Allah and that Muhammad is His slave and Apostle.) So, when you have said this, then you have surely sent the greetings to every good (pious) worshipper of Allah, whether he be in the Heaven or on the Earth . "

Narrated 'Aisha: A man asked permission to enter upon the Prophet. When the Prophet saw him, he said, "What an evil brother of his tribe! And what an evil son of his tribe!" When that man sat down, the Prophet behaved with him in a nice and polite manner and was completely at ease with him. When that person had left, 'Aisha said (to the Prophet). "O Allah's Apostle! When you saw that man, you said so-and-so about him, then you showed him a kind and polite behavior, and you enjoyed his company?" Allah's Apostle said, "O 'Aisha! Have you ever seen me speaking a bad and dirty language? (Remember that) the worst people in Allah's sight on the Day of Resurrection will be those whom the people leave (undisturbed) to be away from their evil (deeds)."