Every Muslim Has To Give In Charity

Every Muslim has to give in charity and whoever does not find anything to give, should do all that is good {i.e. enjoin Al-Ma'ruf (Islamic Monotheism, and all that Islam has ordained)}.

Narrated Abu Musa (RA);
The Prophet Mohammad (SAW) said:  "Every Muslim has to give in charity," 

The people asked,  "O Allah's Messenger! If someone has nothing to give, what will he do?"

The Prophet (SAW) said, "He should work with His hands and benefit himself and also give in charity (from what he earns)."

The people further asked, "If he cannot do even that?"

The Prophet (SAW) replied, " He should help the needy who appeal for help."

Then the people asked, "If he cannot do that?"

The Prophet (SAW) replied, "Then he should perform all that is good {i.e. enjoin Al-Ma'ruf (Islamic Monotheism, and all that Islam has ordained)} and keep away from all that is evil { i.e. disbelief, polytheism, and all that Islam has forbidden} and this will be regarded as charitable deeds." 
[Sahih Al-Bukhari, Book of Zakat, chapter 19 #730]