Musnad Ahmad 937:195

'Abd al-Malik ibn 'Amr narrated to us, 'Ali—meaning Ibn al-Mubarak—narrated to us, from Yahya, from Zayd ibn Sallam, from Abu Sallam, who said: Abu Dharr said: "Upon every soul, on every day the sun rises, there is a charity from it upon itself." I said: "O Messenger of Allah, from where shall I give charity when we have no wealth?" He said: "Indeed, among the doors of charity are: saying 'Allahu Akbar' (God is the Greatest), 'Subhan Allah' (Glory be to Allah), 'Al-hamdu lillah' (Praise be to Allah), 'La ilaha illa Allah' (There is no god but Allah), and 'Astaghfirullah' (I seek forgiveness from Allah); enjoining the good; forbidding the evil; removing the thorn, the bone, and the stone from the path of the people; guiding the blind; making the deaf and the mute hear until they understand; directing the one seeking guidance to a need of his when you know its location; hastening with the strength of your legs to the distressed one who is calling for help; and lifting with the strength of your arms for the weak. All of that is from the doors of charity from you upon yourself. And for you, in your intercourse with your wife, there is a reward." Abu Dharr said: "How can I have a reward for my desire?" The Messenger of Allah (peace and blessings of Allah be upon him) said: "Do you see, if you had a child who reached maturity and you hoped for his goodness, then he died, would you seek reward for him?" I said: "Yes." He said: "Did you create him?" He said: "Rather, Allah created him." He said: "Did you guide him?" He said: "Rather, Allah guided him." He said: "Did you provide for him?" He said: "Rather, Allah was the One who provided for him." He said: "Likewise, place it in its lawful place and avoid its unlawful place; if Allah wills, He will keep it alive, and if He wills, He will cause it to die, and you shall have a reward."