diff --git a/exo/10/01.md b/exo/10/01.md
index 98760e5dde..f989cf67ea 100644
--- a/exo/10/01.md
+++ b/exo/10/01.md
@@ -1,3 +1,3 @@
 # for I have hardened his heart and the hearts of his servants
 
-See how you translated "Yahweh hardened Pharaoh's heart" in Exodus 9:12. 
+See how you translated "Yahweh hardened Pharaoh's heart" in Exodus 9:12. (also see Exodus 4:21)