The Messenger of Allaah, peace and blessings be upon him, said,
لو أنكم كنتم توكلون على الله ØÙ‚ توكله لرزقتم كما يرزق الطير تغدو خماصا ÙˆØªØ±ÙˆØ Ø¨Ø·Ø§Ù†Ø§
"If you were to rely upon Allaah with reliance due to Him, He would provide for you just as He provides for the birds. They go out in the morning with empty stomachs and return full."
Sunan al-Tirmidhi 2344
Sahih (authentic) according to Al-Albani