"And Sadducees came to him, who say that there is no resurrection. And they asked him a question, saying, 'Teacher, Moses wrote for us that if a man’s brother dies and leaves a wife, but leaves no child, the man must take the widow and raise up offspring for his brother. There were seven brothers; the first took a wife, and when he died left no offspring. And the second took her, and died, leaving no offspring. And the third likewise. And the seven left no offspring. Last of all the woman also died. In the resurrection, when they rise again, whose wife will she be? For the seven had her as wife.'" (Mark 12:19-23, ESV)
Okay, this passage tickles me. I can picture Jesus heaving this huge sigh and rolling his eyes. His response to them is (paraphrased), "Come on, guys. Haven't you read the scriptures? When people are raised from the dead, they don't marry. They're like the angels. And as for what your real question is--that there is or isn't a resurrection--remember when God spoke to Moses from the burning bush? God said, 'I Am the God of Abraham, Isaac, and Jacob.' That means those three men are alive, and God is their God."