牛うしは牛うし連づれ馬うまは馬うま連づれ

expression

birds of a feather flock together; like attracts like

Proverb meaning that similar people or things naturally group together. Literally 'cows with cows, horses with horses.'

• あの二人ふたりはすぐに仲なか良よくなった。牛うしは牛うし連づれ馬うまは馬うま連づれというからね。

  Those two quickly became friends. Birds of a feather flock together, after all.