Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: The Messenger of Allah (peace and blessings be upon him) said: "Upon every joint of a human being there is (due) a prayer every day." Some of the people said: This is very difficult, O Messenger of Allah! He (peace and blessings be upon him) said: "Indeed, enjoining good and forbidding evil is a prayer, carrying (a burden) for the weak is a prayer, and every step that one of you takes towards the prayer is a prayer."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11741