John Wesley on Deuteronomy 23:6

Thou shalt not seek their peace - That is, make no contracts either by marriages or leagues, or commerce with them, but rather constantly keep a jealous eye over them, as enemies who will watch every opportunity to ensnare or disturb thee. This counsel was now the more necessary, because a great part of the Israelites lived beyond Jordan in the borders of those people, and therefore God sets up this wall of partition betwixt them, as well knowing the mischief of bad neighbours, and Israel's proneness to receive infection from them. Each particular Israelite is not hereby forbidden to perform any office of humanity to them, but the body of the nation are forbidden all familiar conversation with them.