|Abraham and Sarah...|
See Genesis 23:19, 25:9.
|Isaac and Rebecca|
Genesis 35:29. There, however, it does not mention that Isaac was buried in Makhpelah.
The burial of Rebecca and Leah is not mentioned previously. An ancient source states that Leah was buried 'near Rebecca, to the left of Sarah' (Yov'loth 36:21). For a discussion of how the graves were arranged, see MeAm Lo'ez/The Torah Anthology 3:549.