proverb/ˌdonde ˌno ˌai ˌmata ˌno ˌai paˈtata/
One cannot perform a task without having the necessary materials or skills to do so.
“—Venga, Fernando, vámonos. Donde no hay mata no hay patata y con estos caguetas no hay nada que hacer—fue la despedida de Juan.” — —Come on, Fernando, let's go. Where there is no shrub, there is no potato, and with these cowards there is nothing to do—was Juan's farewell.
Literally, “where there is no shrub, there is no potato”, i.e. you cannot have a potato without a potato plant.