Which son of Reuel the Midianite did Moses invite to journey with Israel?

Answer: Hobab

Moses urged Hobab, son of his father-in-law Reuel, "Come with us, and we will treat you well."

“Then Moses said to Hobab, the son of Moses’ father-in-law Reuel the Midianite, “We are setting out for the place of which the LORD said: ‘I will give it to you.’ Come with us, and we will treat you well, for the LORD has promised good things to Israel.””— Numbers 10:29 (BSB)