en_tn_lite_do_not_use/exo/09/01.md

Yahweh continues talking with Moses about dealing with Pharaoh and bringing the Hebrew people out of Egypt.

if you refuse to let them go, if you still keep them back

These two phrases mean basically the same thing and emphasize what will happen if Pharaoh does this. AT: "If you still refuse to let them go" (UDB) (See: rc://en/ta/man/translate/figs-parallelism)

then Yahweh's hand will be on your cattle

Yahweh will show his power by sending a terrible disease upon the Egyptians' livestock. (See: rc://en/ta/man/translate/figs-metonymy)