What does Genesis 30:35 mean?
After agreeing to Jacob's terms for his wages, Laban immediately finds a way to cheat. We see again that this man, Jacob's father-in-law and Rebekah's brother (Genesis 24:29), is a thoroughly dishonest man. Earlier, he treacherously claimed a local custom in order to cheat Jacob out of seven years of service, as well as indebting him to seven more (Genesis 29:18–30). Now, Laban again demonstrates that he's not above blatant sabotage in order to prosper.The agreement between Laban and Jacob was that Jacob would own every black sheep and mixed-color sheep or goat born among the flocks from this time forward. Fully white sheep and fully black goats were far more common, so the deal was already tipped in Laban's favor. Jacob is asking to only keep the uncommon, "defective" animals. At least in theory, Laban again stands to gain a great deal from this arrangement.
And yet, to improve his odds even more, Laban now acts to remove all of the mixed-color animals and black sheep from the existing herds and gives those to his sons. Spotted and speckled sheep and goats are mostly likely to be born to spotted and speckled parents. If Laban were to remove all of those at the start, only a very small percentage born in the remaining flock—if any—were likely to be black lambs or mixed-color sheep or goats. This is a cheat designed to turn Jacob's own plan against him. To further drive home his plan, Laban will also move these animals several days' journey away from Jacob (Genesis 30:36).