Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abu Dharr (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Charity is due from every joint of each of you; every time you say «سبحان الله» it is charity, and every time you say «الحمدلله» it is charity, and every time you say «لا إله إلا الله» it is charity, and every time you say «الله اكبر» it is charity. Enjoining good is charity, and forbidding evil is charity, and all of these can be replaced by two rak‘ahs that a person prays at the time of Duha."