Sayyiduna Abu Dharr (may Allah be pleased with him) narrates from the Prophet (peace and blessings be upon him) that he (peace and blessings be upon him) said: "Every morning charity is due on every joint. Saying 'Subhan Allah' (Glory be to Allah) is charity, saying 'Al-hamdu lillah' (Praise be to Allah) is charity, saying 'La ilaha illa Allah' (There is no god but Allah) is charity, saying 'Allahu akbar' (Allah is the Greatest) is charity, enjoining good is charity and forbidding evil is charity, and two rak'ahs of Duha (forenoon) will suffice for all of these."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4898