In Musnad al-Imam Ahmad (205) it is narrated that ‘Umar ibn al-Khattaab (may Allaah be pleased with him) said that he heard the Prophet of Allaah (peace and blessings of Allaah be upon him) say:
“If you put your trust in Allaah in the true sense, He will grant your provision as He grants to the birds, who go out in the morning hungry and come back full.”
Classed as saheeh by al-Albaani in al-Saheehah (310).