Encouragement to give charity before there is no one to accept it Sahih Muslim 1011
Translation
Haritha b. Wahb reported Allah's Messenger (ﷺ) as saying
Give Sadaqa for a time is about to come when a person would walk with alms and the one whom it is to be given would say: Had you brought it yesterday, I would have accepted it. For the present I do not need it. (And the giver of Sadaqa) I would not find anyone to accept it.