We should put our full trust in God, because He is sufficient for us in the matter of sustenance.
Some of the Companions were worried about the migration to Madinah, saying that there was no wealth for their relatives.
God reassures them,
There are many animals that do not store their food. GOD provides for them, and for you. He is the All-Hearing, the All-Knowing.
(Al-Ankabut 29:60)
In the commentary, Keramgan said that no animal except human beings, rats and ants store their food. They eat day in and day out. They have such a deep faith in God!
If people could believe in God like this, they would also get such sustenance.
It is narrated on the authority of 'Umar ibn al-Khattab (may Allah be pleased with him) that the Messenger of Allah, may Allah bless him and grant him peace, said: They go out on an empty stomach in the morning and return on a full stomach in the evening.
Sahih, Ibn Ma-Jah (4174)
The value of hadith: Sahih
Imam Shafi (R) said,
What is in destiny will come even if it is not between two mountains, and what is not in destiny will not come if it is not between two lips. What is in destiny will come even if it is not between two mountains, and what is not in destiny will not come if it is between two lips. Why not stay in the middle.
Imam Shafi (R)