Here I explain certain Spanish idioms very briefly. There is usually a link that will give you the meaning in English. In this case, it was not possible, since this idiom is not that usual nowadays.
PARA ENCAMARAR EL TRIGO NO QUIERO PARIENTES NI AMIGOS
I hope you understand the explanation in Spanish (B2, C1), suitable for the intermediate and advanced levels. You will not come across this proverb very frequently these days. It warns you off people who are more interested in the wins than in yourself.