Mark 12:24-27

24 Jesus said to the Sadducees, ‘You are completely wrong. This is because you do not know the Bible. And you do not know how powerful God is. 25 All people who have died will become alive again one day. But then men and women will not marry. They will not have husbands or wives. Instead, they will be like the angels in heaven. 26 But God does make dead people alive again! You have read what Moses wrote about the bush in the wilderness. There, God said to Moses, “I am the God of Abraham. I am the God of Isaac. And I am the God of Jacob.” 27 God is not the God of people who are dead. He is the God of people who are alive. So you see, you are completely wrong.’

12:26Abraham was the first ancestor of the Israelite nation, and of other nations. He was the father of Isaac and the grandfather of Jacob.
12:26See Exodus 3:6.