Hamor suggested a marriage alliance for mutual economic gain. But God had already promised Jacob everything, including the land (34:10; see 14:21–24). Hamor wanted to control Israel’s wealth (34:23). Trusting the Canaanites would not lead to anything good.
For some of these reasons, the law of Moses did not allow Israelites to marry Canaanites (see Exodus 23:27–33; Deuteronomy 7:1–5). The exception would be if they converted (see Joshua 2:1–15; 6:23–25; Matthew 1:5).