Musannaf Ibn Abi Shayba 33:1358

'Isa ibn Maryam said: Do not store today's provision for tomorrow, for He who brought it to you today will bring it to you tomorrow. If you say, "How can that be?" then look at the birds; they do not plow and they do not sow. They go out and return to the provision of Allah. If you say, "And what is sufficient for the birds?" then look at the wild donkeys and the wild cattle; they go out to the provision of Allah and return full.