In the opening passages of this week’s parsha, Rashi cites a question from the Midrash Tanchuma:
למה נסמכה מיתת שרה לעקידת יצחק, לפי שעל ידי בשורת העקידה שנזדמן בנה לשחיטה וכמעט שלא נשחט פרחה נשמתה ממנה ומתה.
Why was the death of Sarah recorded in the Torah alongside Akeidas Yitzchak? When she was informed about the Akeidah, that her son had been prepared for slaughter and was almost not slaughtered, her soul fled from her body and she died.
It would seem more accurate for Rashi to have written that Yitzchak was almost slaughtered, rather than he was almost not slaughtered. Taken literally, Rashi seems to say that Yitzchak was indeed slaughtered, but just barely. Yet we know that this was not the case. The angel stayed Avraham’s hand at the last moment, and Yitzchak’s life was spared. What then does Rashi mean by saying that Yitzchak was “almost not slaughtered”?
The Sifsei Chachomim explains that a messenger informed Sarah that Yitzchak had been bound to the Mizbei’ach and prepared for slaughter, but before he could conclude that Yitzchak’s life was spared, Sarah died from shock. Thus, Rashi means to say that the messenger was about to say that Yitzchak was not slaughtered, but he did not have the chance to conclude his words.
On a deeper level, we may suggest that Yitzchak was indeed slaughtered in a certain sense, since Klal Yisrael – as his descendants – are accredited with the merit of the Akeidah as if it had been carried out to the end. The Midrash states that when Hashem told Avraham Avinu, “Do not stretch out your hand to harm the youth,” Avraham asked permission to draw a drop of blood, so that it might considered as if he had slaughtered Yitzchak. Hashem then added, “Do not do anything (מאומה) to him,” implying that he should not make the slightest blemish (מום). When Avraham then sacrificed the ram instead, he prayed with every stage of the sacrifice, “May this find favor before You as if I had slaughtered my son … as if I had thrown his blood against the Mizbei’ach … as if I had burned him upon it.”
His prayers were answered; Klal Yisrael did indeed receive the full merit of the Akeidah as if Yitzchak himself had been sacrificed. The Gemara thus states that when Ezra returned to Eretz Yisrael to rebuild the Beis HaMikdash, he located the site on which to build the Mizbei’ach by noticing the ashes of Yitzchak piled there. If Yitzchak was never actually slaughtered and burned, how could his ashes have been seen there? Rather we must explain that although he was not physically slaughtered, the merit was granted to us as if the ashes of the ram were his own.
We can thus explain that Sarah rejoiced with the knowledge that her son had ascended to such a lofty spiritual height that he was chosen as a sacrifice to be offered on the Mizbei’ach. When she then heard that he was almost not slaughtered, and that only a ram was slaughtered as if it were him, her heart broke with disappointment and she died. She did not realize that the sacrifice of the ram was fully accredited to him and to his descendants as if he had actually been sacrificed himself.
Alternatively, we can explain that Sarah’s soul fled her body after having experienced such a tremendous spiritual ascent that she was unable to retain her hold on this physical world. Such was the case with the Mishnaic Sage, Ben Azzai, who entered the Pardes: the Orchard of G‑dly Wisdom, and became so enraptured with the awareness of the Almighty that he was unable to return to this world. Regarding this incident, the Gemara states:
תנו רבנן ארבע נכנסו בפרדס ואלו הן בן עזאי ובן זומא אחר ורבי עקיבא וכו'. בן עזאי הציץ ומת, עליו הכתוב אומר 'יקר בעיני ה' המותה לחסידיו'. בן זומא הציץ ונפגע, ועליו הכתוב אומר 'דבש מצאת אכול דייך פן תשבענו והקאתו. אחר קציץ בנטיעות. רבי עקיבא יצא בשלום
Four entered the Pardes: Ben Azzai, Ben Zoma, Rebbe Akiva and Acheir … Ben Azzai gazed and died. Of him it is written, “Precious in the eyes of Hashem is the death of His pious.” Ben Zoma gazed and was struck [by insanity]. Of him it is written, “If you find honey, eat no more than your fill, lest you gorge yourself and vomit.” Acheir uprooted his plantings (by abandoning Torah observance). Rebbe Akiva alone emerged in peace. 
The Maharsha comments:
בן עזאי ציץ ומת מתוך שדבקה נפשו באהבה רבה, דבקות אמיתי בדברים עליונים שהם יסודה, והציץ באור הזהיר נתפרדה מן הגוף ונתפשטה מכל מקרי הגוף, באותה שעה ראתה מנוחה כי טוב ולא שבה עוד למקומה, וזו מעלה גדולה ע"כ נאמר יקר בעיני ה' המותה לחסידיו וגו'
“Ben Azzai gazed and died.” His soul embraced with powerful love the upper worlds from which it was formed. As he gazed at the radiant light, his soul took leave of his body and shook itself free of all the body’s worldly interests. At that moment he found the peace he desired, and chose not to return to his place in this world. This was a great spiritual height, for which reason it was said of him, “Precious in the eyes of Hashem is the death of His pious.”
In Parshas Acharei Mos, the Ohr HaChaim applies the explanation to the deaths of Nadav and Avihu, of whom the verse testifies, בקרבתם לפני ה' “They drew close to Hashem and died.” They entered a plane of such intense spiritual awareness that they were unable to retain a connection with this physical world.
Similarly, Rebbe Tzadok HaKohen of Lublin explains that when Rebbe Akiva was being executed and recited Shema, he died not from the iron combs that raked his flesh, but from the love and yearning for the Creator that pervaded his entire being and drew his soul out to its Heavenly source.
The same was true of Sarah Immeinu. When she heard of the great sacrifice her son had made, having been all but offered as a korban on the Mizbei’ach, she also ascended to such a lofty spiritual level that her soul shook off the constraints of this world and ascended Above.
 Midrash Rabbah , Parshas Vayeira
 Zevachim 62a. See also Vayikra Rabbah 36:4; Rashi on Parshas Bechukosai, Bamidbar 26:42, and Toras Kohanim loc cit.
 Chagigah 14b
 Vayikra 16a