Excellence of spreading the Islamic greeting — context

AAammar said: ‘Three characteristics, whoever combines them, has completed his faith: to be just, to spread greetings to all people and to spend (charitably) out of the little you have.’ ‘AAabdullah Ibn AAamr reported that a man asked the Prophet : ‘Which Islam is the best?’. He replied: Feed (the poor), and greet those whom you know as well as those whom you do not.