Midrash Rabbah - Exodus I:22

AND HIS SISTER STOOD AFAR OFF (II. 4). Why did Miriam stand afar off? Rabbi Amram in the name of Rab said: Because Miriam prophesied, 'My mother is destined to give birth to a son who will save Israel'; and when the house was flooded with light at the birth of Moses, her father arose and kissed her head and said: 'My daughter, thy prophecy has been fulfilled.' This is the meaning of: And Miriam the prophetess, the sister of Aaron, took a timbrel (Ex. XV, 20); 'The sister of Aaron,' but not of Moses?- [She is so called] because in fact she said this prophecy when she was yet only the sister of Aaron, Moses not having been born yet. Now that she was casting him into the river, her mother struck her on the head, saying: 'My daughter, what about thy prophecy?' This is why it says: AND HIS SISTER STOOD AFAR OFF. to know what would be the outcome of her prophecy. [footnote states: "The Rabbis saw in the word mayrachok a reference to the rebuke she had received first from her father and then from her mother on the nonfulfilment of her prophecy."] The Rabbis interpreted the whole verse as referring to the Holy Spirit.' [footnote states: "It was the Holy Spirit that stood there, and every word in this verse can be interpreted as an allusion thereto. This of course does not mean that Miriam was not present but that the Shechinah was there too."] AND SHE STOOD, hinting at And the Lord came, and stood (I Sam.III,10). [footnote states: "The same form of the verb is used."] HIS SISTER, hinting at: Say unto wisdom: Thou art my sister (Prov. VII, 4). FROM AFAR. hinting at: From afar the Lord appeared unto me (Jer. XXXI, 3). TO KNOW WHAT WOULD BE DONE TO HIM, hinting at: For the Lord is a God of Knowledge (I Sam II, 3). [footnote states: "This passage is given in fuller form in J. Sot. 1, 9."]