Genesis 30:43

Jacob separated the lambs, and set the faces of the flocks toward the streaked and all the black in Laban’s flock. He put his own droves apart, and didn’t put them into Laban’s flock.

Whenever the stronger of the flock conceived, Jacob laid the rods in front of the eyes of the flock in the watering troughs, that they might conceive among the rods;

but when the flock were feeble, he didn’t put them in. So the feebler were Laban’s, and the stronger Jacob’s.