Mishkat al-Masabih

‘Amr b. Shu'aib on his father’s authority said his grandfather told that the Prophet (ﷺ) sent someone to announce in the ravines of Mecca, “The sadaqa relating to the breaking of the fast is incumbent on every Muslim, male or female, freeman or slave, young or old, consisting of two mudds of wheat or such like, or a sa' of grain." Tirmidhi transmitted it.