7 When Isaac arrived in Gerar, some men asked him about his wife, and he said, "She's my sister." (He didn't say, "she's my wife", because he was afraid they'd kill him, since Rebekah was so beautiful.)
8 One day, Abimelech looked out his window and saw Isaac sporting with Rebekah.
34-35 Esau took two Hittite women for wives, Judith and Bashemath. Isaac and Rebekah didn't approve of these marriages.
A few more words about this episode
Go visit Abimelech (v.1)
Isaac visits king Abimelech, repeating the same "she's my sister" lie that his father used twice, once to king Abimelech in Genesis 20. But was it the same king Abimelech? If so, he must have been very old, since Abraham's visited when he was 100 years old, and he died at the age of 175, before Isaac's visit.
Whether Abimelech was the same king Abraham and Sarah lied to or not, there is another problem with this very unlikely story. The Philistines didn't yet exist in the region at the time this story supposedly occured, and wouldn't for another 600 years or so.
But Isaac grew rich from the lie, just like his father had. (You'd think Abimelech wouldn't fall for the same stupid lie twice. But hey, this is the Bible!)
Because your father obeyed me (v.5)
God is blessing Isaac for what his father, Abraham, did - which was show his willingness to kill and sacrifice Isaac as a burnt offering to God. Only a bad father would be willing to do that; only a bad God would ask a father to do it.
Isaac sporting with Rebekah (v. 8)
This verse uses the same hebrew verb ("t'sahak" that the King James Version translates as "sporting") that was used to describe what Ishmael did to Isaac in Genesis 21:9 that upset Sarah so much.
Esau took two Hittite women for wives. Isaac and Rebekah didn't approve of these marriages (vv.34-35)
Because they were Hittites, presumably -- not because he married two women.