Exodus 4:20-25

ASV_Strongs(i)
  20 H4872 And Moses H3947 took H802 his wife H1121 and his sons, H7392 and set H2543 them upon an ass, H7725 and he returned H776 to the land H4714 of Egypt: H4872 and Moses H3947 took H4294 the rod H430 of God H3027 in his hand.
  21 H3068 And Jehovah H559 said H4872 unto Moses, H3212 When thou goest H7725 back H4714 into Egypt, H7200 see H6213 that thou do H6440 before H6547 Pharaoh H4159 all the wonders H7760 which I have put H3027 in thy hand: H2388 but I will harden H3820 his heart, H5971 and he will not let the people H7971 go.
  22 H559 And thou shalt say H6547 unto Pharaoh, H559 Thus saith H3068 Jehovah, H3478 Israel H1121 is my son, H1060 my first-born:
  23 H1121 and I have said unto thee, Let my son H7971 go, H5647 that he may serve H3985 me; and thou hast refused H7971 to let him go: H2026 behold, I will slay H1121 thy son, H1060 thy first-born.
  24 H1870 And it came to pass on the way H4411 at the lodging-place, H3068 that Jehovah H6298 met H1245 him, and sought H4191 to kill him.
  25 H6855 Then Zipporah H3947 took H6864 a flint, H3772 and cut off H6190 the foreskin H1121 of her son, H5060 and cast H7272 it at his feet; H559 and she said, H2860 Surely a bridegroom H1818 of blood art thou to me.