Any type of charity that isn’t Zakat and therefore obligatory, is called Sadaqah. It is an act of voluntary charity which has no rules regarding how much you are giving to charity, how often, or who is eligible to give Sadaqah as anyone can make this voluntary contribution. Sadaqah is given without knowing how much reward can be reaped, but a belief in Allah’s generosity, kindness, love and justice.
We know that Prophet Muhammad (saw) was very generous and gave a lot of charity, often leaving him with nothing or very little for himself. In multiple hadith, Prophet Muhammad (saw) has been described as being “as generous as the wind”.