Luke 12:26

If then you are unable to do even a very little thing, why be over-anxious about other matters?

Luke 12:29

"Therefore, do not be asking what you are to eat nor what you are to drink; and do not waver between hope and fear.

1 Peter 5:7

Throw the whole of your anxiety upon Him, because He Himself cares for you.

Treasury of Scripture Knowledge

Summary

If ye then be not able to do that thing which is least, why take ye thought for the rest?

Bible References

Why

Luke 12:29
"Therefore, do not be asking what you are to eat nor what you are to drink; and do not waver between hope and fear.
1 Peter 5:7
Throw the whole of your anxiety upon Him, because He Himself cares for you.