'Abdullah said, "Peace is one of the Names of Allah which Allah
has placed on the earth. Extend it among you. When a man greets people
and they answer him, then he has a higher degree than them because he reminds
them of peace. If no one answers him, he will be answered by one who is
better and more excellent.'"
'Abdullah ibn as-Samit said, "I said to Abu Dharr, 'I passed by
'Abdu'r-Rahman ibn Umm al-Hakam and I greeted him and he did not answer
me at all. He said, 'Nephew, what harm have suffered from that? Someone
better than him answered you ? the angel on his right."
Mu'awiya ibn Qurra said that his father said to him, "My son,
when a man passes by you and says, 'Peace be upon you (plural).' Do not
say, 'And on you (singular)' as if you were singling out that greeting
out for him alone. Rather say, 'Peace be upon you (plural).'"