"And one told Jacob"
Rabbi Yosi explains that, "And one told Jacob," refers to Jacob being told that his children would be redeemed. Through this redemption, Jacob would receive both truth and grace, which are two Sfirot, also contained in two higher Chariots, Abraham and Jacob.
To achieve a higher level of spirituality and existence, we sometimes need to "borrow" Light from the Creator in order to use it to awaken and arouse even greater Light in our lives and in this world. This is similar to a businessman borrowing money from a bank for the purpose of building a successful business. In other words, you need money in order to make money. Hence, the primary purpose of this passage is to entrust the readers with Light, so that they may use it to for spiritual purposes and the formation of greater Light.
45. "And one told Jacob, and said, 'Behold, your son Joseph comes to you'" (Beresheet 48:2). Rabbi Yosi said, It was an angel WHO TOLD JACOB that he was about to pronounce good words about the children of Yisrael at the time they would return to the Holy One, blessed be He, with all their troubles, when The Messiah's end was to come. And He would say to the attribute, JACOB, THE SECRET OF TIFERET, your children are come to you, and the good ones, THE CHILDREN OF YISRAEL, will be redeemed.
45. וַיַּגֵּד לְיַעֲקֹב וַיֹּאמֶר הִנֵּה בִּנְךָ יוֹסֵף בָּא אֵלֶיךָ. רִבִּי יוֹסֵי אֲמַר, מַלְאָכָא הוּא, דַּהֲוָה עָתִיד לְמֵימַר טַב עַל בְּנֵי יִשְׂרָאֵל, כַּד יְתִיבוּן לְקוּדְשָׁא בְּרִיךְ הוּא, בְּכָל עָקַתְהוֹן, כַּד יֵיתֵי קִצָּא דִמְשִׁיחָא, בְּכָל עָקְתָא דְּתֵיתֵי עֲלֵיהוֹן, יֵימְרוּן לִמְכִילָתָא בְּרִיךְ אָתִי לְוָתָךְ, וְיִתְפָּרְקוּן טָבָאי.
46. Happy is the portion of Yisrael, who are named the children of the Holy One, blessed be He, that are like angels, OF WHOM IT SAYS, "And all the sons of Elohim shouted for joy" (Iyov 38:6). YISRAEL IS ALSO CALLED the sons of Hashem, AS IT SAYS, "YOU ARE THE CHILDREN OF HASHEM YOUR ELOHIM" (DEVARIM 14:1).
46. זַכָּאָה חוּלְקֵהוֹן דְּיִשְׂרָאֵל, דְּאִתְקְרִיאוּ בְּנוֹי דְּקוּדְשָׁא בְּרִיךְ הוּא, דְּאִינוּן כְּמַלְאָכַיָיא, וַיָּרִיעוּ כָּל בְּנֵי אֱלֹקִים, הוי"ה מַאי.
47. Come and behold! Whence do we know that the Holy One, blessed be He, called Jacob, 'El?' He said to him: 'You shall be among the lower beings, and I shall be Elohim among the upper beings.' Whence do we know that? HE ANSWERS, It is written, "And Elohim went up from Abraham" (Beresheet 17:22). Thus the fathers are a Chariot to the Holy One, blessed be He. We learned that "you will show Truth to Jacob, Grace (Heb. chesed) to Abraham" (Michah 7:20) has in it two Sfirot, CHESED AND TRUTH, WHICH IS TIFERET in two bigger and higher Chariots - ABRAHAM AND JACOB.
47. תָּא חֲזֵי, מִנַּיִן שֶׁקָּרָא קוּדְשָׁא בְּרִיךְ הוּא לְיַעֲקֹב אֵ"ל, אַתְּ תְּהֵא בְּתַתָּאָה, וַאֲנָא אֱהֵא אֱלָהָא בְּעִלָּאָה, מַאי קָא מַיְירֵי. וַיַּעַל אֱלֹהִים מֵעַל אַבְרָהָם, אֲבָהָתָן אִינוּן רְתִיכָאן דְּקוּדְשָׁא בְּרִיךְ הוּא. תָּנָא, תִּתֵּן אֱמֶת לְיַעֲקֹב חֶסֶד לְאַבְרָהָם, הָא תְּרֵין סְפִירָן, בִּתְרֵין רְתִיכָן, רַבְרְבָן עִלָּאִין.
48. The third one is Isaac, WHO BECAME A CHARIOT TO THE SFIRAH OF GVURAH. Whence DO WE KNOW THAT? FROM THE WORDS "And Jacob swore by the fear of his father Isaac" (Beresheet 31:53). For the fear of Isaac is a Sfirah of the Holy One, blessed be He, NAMELY GVURAH CALLED FEAR, AND BECAME the Throne of Glory, ITS supernal Chariot. Isaac's Sfirah, GVURAH, is more important and explicit than the other Sfirot of the fathers, CHESED AND TIFERET. For that reason it is written, "And Jacob swore by the fear of his father Isaac;" NAMELY BY THE SFIRAH OF GVURAH CALLED FEAR, WHICH IS THE MOST VALUABLE.
48. תְּלִיתָאָה יִצְחָק, מַאי וַיִּשָּׁבַע יַעֲקֹב בְּפַחַד אָבִיו יִצְחָק. וּבְגִין פַּחַד יִצְחָק דַּהֲוָה סְפִירָה, וְקוּדְשָׁא בְּרִיךְ הוּא דְּהוּא כָּרְסֵי יְקָרָא רְתִיכָא עִלָּאָה, וּסְפִירָה דְיִצְחָק הִיא מֵעִלָּאָה, מְפָרְשָׁא יַתִּיר מִכָּל סְפִירָן דַּאֲבָהָתָא, הה"ד וַיִּשָּׁבַע יַעֲקֹב בְּפַחַד אָבִיו יִצְחָק.
49. Rabbi Aba opened the discussion saying, "The Elohim of Abraham, and the Elohim of Nachor, the Elohim of their father, judge between us. And Jacob swore by the fear of his father Isaac." (Beresheet 31:53). From this verse, one may conclude THAT ISAAC'S SFIRAH IS MORE VALUABLE THAN THE OTHERS, FOR HE DID NOT SWEAR BY ELOHIM OF ABRAHAM, BUT BY THE FEAR OF ISAAC.
49. ר' אַבָּא פְּתַח וַאֲמַר, אֱלֹהֵי אַבְרָהָם וֵאלֹהֵי נָחוֹר יִשְׁפְּטוּ בֵּינֵינוּ אֱלֹהֵי אֲבִיהֶם, וַיִּשָּׁבַע יַעֲקֹב בְּפַחַד אָבִיו יִצְחָק, מֵהַאי קְרָא אַתְּ יָכֵיל לְמִנְדַע דָּא.