Berean Study Bible (BSB) - Exodus 8:15 >

When Pharaoh saw that there was relief, however, he hardened his heart and would not listen to Moses and Aaron, just as the LORD had said.

Jewish Publication Society of America Version (JPS1917) - Exodus 8:15 >

(8-11) But when Pharaoh saw that there was respite, he hardened his heart, and hearkened not unto them; as the LORD had spoken.