The shloka (stanza) quoted above is from Ramayana, the first known written epic on this earth; that was written about 51 centuries back by saint Valmeeki. He quotes the advices of Guru Vasista explaining to Lord Rama when he was crowned as an emperor. He says that it is very easy to get people always uttering sweet words and praising, but it is very difficult to get people who can tell the truth (comments and facts) that is not liked or tolerated by others and also the people who can listen to those comments and facts. This does not apply only to an emperor like Lord Rama, but also for all and at all the time. It is true with our customers also.