“One who calls others to the right path of good deeds gets as much merits as those who act upon his guidance, and the merits of the doers are not reduced thereby. And one who calls others to do wrong sins as much as the collective sins of those who follow him in sinning and their sins shall not be reduced at all”.(Sahih Muslim).
While merit is vouchsafed when others respond to guidance, the very act of guidance to good,whether responded to or not, is one of great merit because hadith tells us that:-
Hence no opportunity of giving good advice to and guiding others should be lost, but care should be taken to adopt a method for this which is not insulting or irksome to the other man. One should not criticize others in public nor should one adopt an overbearing and proud stance; advice should be given in privacy and in a soft tone showing one’s sympathy and commiseration; hence one should choose a time for advice when the hearer is not worried. Wisdom should be exercised in this and intent should be of doing good, since the Quran Says: