The very first sign given in the earth was when God created the heavens and the earth, and the signs were the dividing of the night and the day for seasons and years! (Genesis 1:14). 14 And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years:
Jesus was a sign for the nations given by prophecy that a virgin shall conceive and bear a son and His name would be Immanuel, one who would refuse evil and choose the good(Isaiah 7:10-15). 10 Moreover the Lord spake again unto Ahaz, saying,11 Ask thee a sign of the Lord thy God; ask it either in the depth, or in the height above.12 But Ahaz said, I will not ask, neither will I tempt the Lord.13 And he said, Hear ye now, O house of David; Is it a small thing for you to weary men, but will ye weary my God also?14 Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.15 Butter and honey shall he eat, that he may know to refuse the evil, and choose the good.
God hardened Phar’-aohs heart and his servants hearts as well so that He could show His signs before them, and so that they would know He was the Lord!(Exodus 10:1-3). And the Lord said unto Moses, Go in unto Pharaoh: for I have hardened his heart, and the heart of his servants, that I might shew these my signs before him:2 And that thou mayest tell in the ears of thy son, and of thy son’s son, what things I have wrought in Egypt, and my signs which I have done among them; that ye may know how that I am the Lord.3 And Moses and Aaron came in unto Pharaoh, and said unto him, Thus saith the Lord God of the Hebrews, How long wilt thou refuse to humble thyself before me? let my people go, that they may serve me.