אָ֣ז יִבָּקַ֤ע כַּשַּׁ֙חַר֙ אוֹרֶ֔ךָ וַאֲרֻכָתְךָ֖ מְהֵרָ֣ה תִצְמָ֑ח וְהָלַ֤ךְ לְפָנֶ֙יךָ֙ צִדְקֶ֔ךָ כְּב֥וֹד יְהוָ֖ה יַאַסְפֶֽךָ׃
Então romperá a tua luz como a alva, e a tua cura apressadamente brotará. e a tua justiça irá adiante de ti; e a glória do SENHOR será a tua retaguarda.
Rabbeinu Bahya
The Mechilta also mentions that the word אז is sometimes used in the future tense and sometimes in the past tense. Examples of the word occurring in the past tense are Genesis 4,26, Exodus 4,26, Numbers 21,17, Joshua 10,12 and others. At the same time there are numerous examples of the word אז referring to future events such as in Isaiah 60,5 אז תראי ונהרת, Isaiah 58,8 אז יבקע כשחר אורך, Isaiah 35,6 אז ידלג כאיל and many others. Moses reasoned that since he had used the word אזwhen he had criticised G’d’s apparent indifference to Pharaoh’s additional decrees worsening the condition of the Jewish slaves (Exodus 4,10), it was now up to him to make amends by using the same word in exalting Him. The word אז, i.e. 1+7, is an allusion to the Unique One who reigns supreme above the seven heavens.
According to a Midrash Tanchuma on Genesis 4,26 the Israelites reasoned that seeing that word had been used when G’d punished mankind for the first time collectively when He caused one third of the dry land mass to be inundated in response to the idolatry introduced by the generation of Enosh, it was appropriate to use the same word at a time when G’d’s sovereignty on earth had been demonstrated by means of the water which had been made to retreat even from its own habitat.
The words משה ובני ישראל לאמור, teach that Moses and the Children of Israel had the good fortune to personally use this formula of exalting G’d, i.e. praising the attribute called זאת לה'. This was like the bride who applauds her husband the King and says: שיר השירים אשר לשלמה. [This mystical approach is based on the apparent redundancy otherwise of the extra words את השירה הזאת. Ed.] The author promises to deal with this in greater detail in Numbers 21,19.
According to a Midrash Tanchuma on Genesis 4,26 the Israelites reasoned that seeing that word had been used when G’d punished mankind for the first time collectively when He caused one third of the dry land mass to be inundated in response to the idolatry introduced by the generation of Enosh, it was appropriate to use the same word at a time when G’d’s sovereignty on earth had been demonstrated by means of the water which had been made to retreat even from its own habitat.
The words משה ובני ישראל לאמור, teach that Moses and the Children of Israel had the good fortune to personally use this formula of exalting G’d, i.e. praising the attribute called זאת לה'. This was like the bride who applauds her husband the King and says: שיר השירים אשר לשלמה. [This mystical approach is based on the apparent redundancy otherwise of the extra words את השירה הזאת. Ed.] The author promises to deal with this in greater detail in Numbers 21,19.
Or HaChaim
ולקחת מראשית, "and you will take from the first, etc." we can understand this according to the Zohar volume two page 59 that all the commandments a person performs in this life together with all the good deeds he does are collected and stored up in the celestial regions awaiting his arrival there at which time they will serve him as an entrance card to an audience with the King of Kings, the Almighty. This idea is based on Isaiah 58,8: "that your righteousness walks ahead of you when the Glory of G'd gathers you in." ולקחת מראשית כל, "and you will take from the first of all, etc." The Torah means that the word ראשית refers to the best, the choicest. When presenting an offering to G'd you will only take the choicest of the products this world has to offer. Another meaning which the Torah alludes to when choosing the word ראשית is the Torah itself. We have it on the authority of Bereshit Rabbah 1 that the Torah itself is called ראשית.
Shadal
Boker (morning): [It is derived] from baka or (light breaks through), as is the meaning of "your light will break through like the dawn" (Isaiah 58:8).