'Fulfill' in the Bible

Stay in this land. Then I will be with you and will bless you, for I will give all these lands to you and to your descendants, and I will fulfill the solemn promise I made to your father Abraham.

Then Judah said to Onan, "Have sexual relations with your brother's wife and fulfill the duty of a brother-in-law to her so that you may raise up a descendant for your brother."