CHANGING HER NAME FROM SARAI TO SARAH
Gen. 17 relates that God was revealed to Abraham, commanded him regarding circumcision, and also informed him of the change of his name, and of that of Sarai to Sarah. In the midrashic expansion, Abraham says to God: “I see that, in the stars, Abram does not bear children.” God replied: “What you say is so. Abram and Sarai do not bear children, but Abraham and Sarah do bear children” (Gen. Rabbah 44:10).
As regards the significance of this change, the Rabbis explain that initially she was a princess [sarai] over her people, while now she will be a princess over all the inhabitants of the world [sarah] (Tosefta Berakhot [ed. Lieberman] 1:13). In an additional exegetical explanation, because Sarai performed good deeds, God added a large letter to her name, and she would now be called “Sarah” (Mekhilta de-Rabbi Ishmael, Masekhta de-Amalek, Yitro 1). The Rabbis determined that whoever now called Sarah by her former name transgressed a positive commandment (JT Berakhot 1:6, 4[a]). The midrash relates that the letter yud that was taken from Sarai’s name flew up before God. It complained: “Master of all the worlds! because I am the smallest of all the letters, You removed me from the righteous woman’s name?” God replied: “Before, you were in a woman’s name, and at the end of her name, now I put you in a man’s name, and at the beginning of the name [Num. 13:16]: ‘but Moses changed the name of Hosea [hoshe’a] son of Nun to Joshua [yehoshua]’” (Gen. Rabbah 47:1). According to another tradition, half of the letter yud [with the numerical value of ten] that God took from Sarai was given back to Sarah, and the other half was given to Abraham [each received the letter heh = 5 + 5] (JT Sanhedrin 2:6, 20[c]).
After God changed Sarai’s name, He further said (Gen. 17:16): “I will bless her; indeed, I will give you a son by her. I will bless her.” The Rabbis understand that the first blessing was that she would give birth to a son, and the second, that she would have milk. According to another exegesis, God blessed Sarah by forming a womb for her. In a third view, the blessing did not focus solely on the issue of birth, but extended to her entire being, which became young again. A fourth opinion derives the nature of the blessing from the continuation of this verse: “I will bless her so that she shall give rise to nations.” The meaning of the blessing, which relates to Sarah’s standing in the eyes of the nations, is that Sarah will be respected by the Gentile peoples, who will no longer call her barren. The midrash adds that Sarah conceived that very same year (Gen. Rabbah 47:2). -- Jewish Women's Archive, Jewish Women: A Comprehensive Historical Encyclopedia, "Sarah: Midrash and Aggadah"Of course, Moses was given his name by an Egyptian woman. And his name actually sounds like wet stuff, like MaMa too . This was long before Moses (aka "Mama Says Delivered from Mother Nile") took "the letter yud" from Sarai's name to put it into Hosea's to make it JosHua.
Then, back in Egypt, the Hebrews some years later translated what Moses did into Hellene this way:
καὶ ἐπωνόμασεν Μωυσῆς τὸν Αυση υἱὸν Ναυη Ἰησοῦν
kai eponomasen Moyses ton Ayse huion Naye, Iesoun
"and he was named by Moses, this Hosea son of Nun was, was named Jesus"Then some years later, Luke has Gabriel the angel telling mother Mary to name her baby this way:
καὶ καλέσεις τὸ ὄνομα αὐτοῦ Ἰησοῦν
kai kaleseis to onoma autou, Iesoun
"and call that name of his Joshua."