Abraham would not allow his son to marry anyone from the people of Canaan. This is because it would cause his son to worship other gods. Intermarriage and worshiping false gods are things that frequently caused Abraham's descendants to struggle. (See: [[rc://en/tw/dict/bible/kt/falsegod]])
There are many instances recorded in this chapter which highlight Abraham's significant wealth. He owned more than 10 camels and had large amounts of gold.
Many scholars believe this is a euphemism. Putting one's hand on a man's genitals was a way to make an important oath. It represented power and progeny. (See: [[rc://en/ta/man/jit/figs-euphemism]])