Genesis 31:43

‘And Laban answered and said to Jacob, “The daughters are my daughters and the children are my children and the flocks are my flocks, and all that you see is mine. And what can I do this day to these my daughters or to their children which they have borne.” '

Laban's case is based on recognised tribal custom. As head over the confederacy all that is in the confederacy is ‘his', that is, belongs to the confederacy, and he is responsible for it. This is especially true in this case when they had all been personally his. While Jacob by his service has obtained certain proprietary rights over them they are still the confederacy's and should remain within the confederacy. Indeed Laban as the patriarch has the responsibility for their protection and must watch over them, which he cannot do if they leave the confederacy. Compare how Delilah remains in her father's house when married to Samson (Judges 14:2 on; 15:1). But because God has spoken to him so vividly he is now prepared for these rights to be overridden.