Hittala Gida Maddalla

Literal meaning - "The plant growing in the backyard is not medicine".

This one is used mostly in situations where external advice or
guidance is what finally convinces one about something while all the
internal efforts failed. For example, if someone refuses to listen to
the advice of parents or relatives on a topic and then accepts the
same advice from an outsider, this saying is used to describe the
situation.

This is also sometimes used when home treatment doesn't work for an
illness and medical advice is required.