The Prophet ﷺ said, "Each morning, charity is due upon every joint of one of you. Every utterance of 'Glory be to Allah' is charity, every utterance of 'Praise be to Allah' is charity, every utterance of 'There is no god but Allah' is charity, and every utterance of 'Allah is the Greatest' is charity. Enjoining good is charity, and forbidding evil is charity. All of this can be fulfilled by two units of prayer performed in the forenoon."
عن النبي ﷺ قال: يصبح على كل سلامى من أحدكم صدقة، فكل تسبيحة صدقة، وكل تحميدة صدقة، وكل تهليلة صدقة، وكل تكبيرة صدقة، وأمر بالمعروف صدقة، ونهي عن المنكر صدقة، ويجزئ من ذلك ركعتان يركعهما من الضحى.
Muslim narrated it in "The Prayer of Travelers" (720), from Abdullah bin Muhammad bin Asma Dubai, who said, Mahdi (that is, the son of Maymun) narrated to us, he said, Wasil, the freed slave of Abu Uyayna, narrated to us, from Yahya bin Aqeel, from Yahya bin Yamar, from Abu Aswad Duali, from Abu Dharr, and he related it.Abu Dawud narrated it (5243) from Ahmad bin Mani, from Abbad bin Abbad, from Wasil, with the same chain, and it contains this addition, "His greeting to whomever he meets is charity, his removing harmful things from the road is charity, and his intimacy with his wife is charity." They said, "O Messenger of Allah, does he fulfill his desire and it still counts as charity for him?" He said, "Do you not see, if he had placed it somewhere improper, would he not have sinned?" He said, "And two rakahs of Duha suffice for all of that."Except that in this version he did not mention "Abu Aswad Duali" between Yahya bin Yamar and Abu Dharr. It is established that Yahya heard from Abu Dharr and from other companions as well, so it appears that he narrated the hadith in two different ways.As for his saying "bis-sulama," he meant by it every bone and joint on which the body relies for movement. The root of sulama is a bone in the foot-pad of the camel, and its plural is sulamiyyat.Sharh al-Sunnah (4/142).