Those that springs to mind are.

More haste, less speed.

The faster you do something the more likely you are to make mistakes.
Then there is

If you don't have the time to do it right, when are you going to have the time to do it again?

Possibly

Fools rush in where angles fear to tread.

Those that springs to mind are.

More haste, less speed.

The faster you do something the more likely you are to make mistakes.
Then there is

If you don't have the time to do it right, when are you going to have the time to do it again?

Possibly

Fools rush in where angels fear to tread.