I'm trying to find out the English version of this saying, which in Italian is: "L'occhio del padrone ingrassa il cavallo,"
And in Spanish is: "El ojo del amo engorda el ganado".
The idea is that if you want to get something done properly, like a successful business for example, you have to take care of it yourself. You can't let someone else do it, because they won't do it as good as you.
I've seen it in English as "It's the master's eye that makes the mill go", but it doesn't seem to be very common. Very little reference to that online.
Do you know a more used phrase for this idea?