Ive been told that moses' wife was hamitic but how do we know based on scripture?
The idea that Moses' wife (Tzipporah) was Hamitic comes from a comment Miriam made about him. Moses was spending a lot of time with God and since one had to be in a state of purity to talk to God, Moses was rarely intimate with his wife. Miriam refers to Moses' wife as a Cushite (Ethiopian)
This is explained as either being idomatic or as being to a reference to an Ethiopian princess that was married to Moses when he was briefly the king of Ethiopia (this story is Midrashic)
Rashi brings down several explanations.