וישכם אברהם בבקר אל המקום אשר עמד שם את פני ה'.
“Avraham rose in the morning, and came to the place where he stood before Hashem (in prayer).”
From here we learn that Avraham Avinu instituted the morning prayer of Shacharis. Similarly, Yitzchak instituted Mincha, and Yaakov instituted Maariv. A hint for this can be found in the second letter of each one’s name. The letter ב from אברהם stands for בקר (morning), the צ from יצחק stands for צהריים (afternoon), and the ע from יעקב stands for ערב (night).
The Maharsha explains that in fact, each of the Avos prayed all three prayers, just as they fulfilled all other Biblical and Rabbinical mitzvos. Nonetheless, since each one applied particular effort to a certain tefillah, he is considered to have instituted it for generations to come. What is the special significance of each tefillah, and how did it correspond to the Forefather who instituted it?
Avraham sanctified Hashem’s Name through his kindness and hospitality. Therefore, he was uniquely attuned to the morning prayers, of which it is said,להגיד בבקר חסדך ואמונתך בלילות :“To speak of Your kindness in the morning, and Your faithfulness at night.” For serving as the pillar of kindness, Avraham was granted the Shacharis prayer, in which he and his descendants would be able to draw Hashem’s mercy and lovingkindness into the world.
Hashem’s Name “Pachad Yitzchak – the Awe of Yitzchak” alludes to Yitzchak’s fear of Heaven, and the sense of stern justice that pervaded his very being. He offered his life to Hashem as a korban upon the Mizbei’ach, and became the living embodiment of awe and trepidation. 
Before nightfall, a spirit of harsh judgment rests upon the world, as the Zohar states. Yitzchak instituted Mincha to advocate on our behalf, and protect us from the very attribute of judgment that he embodied.
Yaakov was the greatest of our forefathers. When he fled his father’s home to wander alone in exile, he prepared the road upon which his descendants were destined to travel in their own exiles throughout the ages. The blessings he received from Yitzchak were passed down as an eternal inheritance to every Jew, giving us the strength and fortitude to persevere and remain loyal to our ideals, until the dawn of redemption finally arrives. He instituted Maariv, the nighttime prayer, to beseech Hashem for mercy in the long, dark night of Golus.
The Meshech Chochma writes as follows:
"ויאמר אלקים לישראל במראות הלילה." הנה אצל אברהם ויצחק לא מצאנו זה רק ביעקב כאן ובויצא היינו מפני שהיה מוכן לצאת לחו"ל לגור לכן בא אליו התגלות אלקות בלילה להראות שאף בלילה בחשכת הגלות שורה שכינה בישראל כמו שאמרו גלו לבבל שכינה עמהם.... ולזה אמר "יענך ה' ביום צרה ישגבך שם אלקי יעקב" שבזמן שהם בצרה ובחשכת לילה ישגבך אלקי יעקב שנגלה אליו בלילה ודו"ק.
“And G‑d spoke to Yisrael in a vision of the night.” This expression is never used anywhere in the Torah in regard to Avraham or Yitzchak. Yaakov alone received a “vision of the night” as he descended from Eretz Yisrael to sojourn abroad. Hashem then revealed Himself to Yaakov at night, signifying that even in the dark night of exile, the Shechina would remain with Bnei Yisrael, as our Sages teach: “When they were exiled to Babylon, the Shechinah traveled with them.” … David HaMelech prayed, “May Hashem answer you on the day of affliction; may the Name of the G‑d of Yaakov support you.” When darkness and suffering would befall Bnei Yisrael, Hashem would remain by their side to protect them, as He remained with Yaakov in the dark night of his own exile.
Each of our Forefathers served Hashem in his own unique way, and thereby prepared a channel through which our own prayers ascend to Heaven, as we emulate their traits of kindness, justice, and fortitude in the darkness of exile. May Hashem remember on our behalf the covenant He forged with our Forefathers, and redeem their children from exile, speedily and in our days.
A Son and a Slave
ויקרא אליו מלאך ה' מן השמים ויאמר אברהם אברהם ויאמר הנני. ויאמר אל תשלח ידך אל הנער ואל תעש לו מאומה כי עתה ידעתי כי ירא אלהים אתה ולא חשכת את בנך את יחידך ממני.
An angel of Hashem called from Heaven and said, “Avraham, Avraham!”
“I am here,” he said.
“Do not stretch your hand against the youth. Do not harm him at all. For now I know that you fear G‑d, since you have not withheld your only son from Me.”
The Midrash describes Avraham’s feelings as he prepared a knife to slaughter his beloved son as a korban to Hashem:
הוא שולח יד ליטול את הסכין ועיניו מורידות דמעות ונופלות דמעות לעיניו של יצחק מרחמנותו של אבא, ואעפ"כ הלב שמח לעשות רצון יוצרו. והיו המלאכים מתקבצין כתות כתות מלמעלן, מה הוון צווחין, "נשמו מסלות שבת עובר אורח הפר ברית מאס ערים", אין רצונו בירושלים ובבית המקדש שהיה בדעתו להוריש לבניו של יצחק, "לא חשב אנוש", לא עמדה זכות לאברהם לית לכל בריה חשיבות קדמוי.
As he stretched out his hand to grasp the knife, tears fell from his eyes into the eyes of Yitzchak, with a father’s mercy for his son. Nonetheless, Avraham’s heart was filled with joy to fulfill the will of his Creator.
The angels gathered above him in groups, and cried, “The paths have been laid desolate, as wayfarers have ceased to travel. He has renounced the covenant, and scorned the cities. He does not consider the man.” “Does He have no desire for Yerushalayim and the Beis HaMikdash that He intended to give to Yitzchak’s children as their inheritance?” they asked. “He does not consider the man.” “If the merit of Avraham did not stand, then no creature can stand before Him.”
We find here a poignant juxtaposition of conflicting emotions. On one hand, Avraham cried over the loss of his precious son, whom he had hoped would carry on his legacy. On the other hand, he rejoiced over the opportunity to fulfill Hashem’s command. How can one heart carry the burden of these two contrary emotions?
The Rambam describes the importance of serving Hashem with love:
העובד מאהבה עוסק בתורה ובמצות והולך בנתיבות החכמה לא מפני דבר בעולם ולא מפני יראת הרעה ולא כדי לירש הטובה אלא עושה האמת מפני שהוא אמת וסוף הטובה לבא בגללה, ומעלה זו היא מעלה גדולה מאד ואין כל חכם זוכה לה, והיא מעלת אברהם אבינו שקראו הקב"ה אוהבו לפי שלא עבד אלא מאהבה והיא המעלה שצונו בה הקב"ה על ידי משה שנאמר ואהבת את ה' אלהיך, ובזמן שיאהוב אדם את ה' אהבה הראויה מיד יעשה כל המצות מאהבה.
He who serves Hashem with love toils in Torah and mitzvos and walks the ways of wisdom, not for any personal benefit; not for fear of punishment, nor for hope of reward. He does what is true because it is true, and his reward consequently follows. This is a very high level, which many scholars fail to achieve. It was the path walked by Avraham Avinu, whom Hashem called His beloved, since he served Hashem purely out of love. This is the level towards which we must aspire, as Hashem commanded us through Moshe, “And you shall love Hashem, your G‑d.” If one’s love for Hashem is strong, he will fulfill all the mitzvos purely for the sake of love.
The Zohar states that we must relate to Hashem both as His slave and His son. A slave stands in awe of his master, and would never dare question his master’s will. A son loves his father with all his heart and soul, and rejoices to fulfill his father’s will, with no thought of his own benefit. Nevertheless, he may ask a respectful question and expect to receive a loving explanation.
In every aspect of our service of Hashem there must be a delicate balance between love and awe; between the desire to draw close to Hashem, and the fear of overstepping the boundaries of servitude. We must be both slaves and children of Hashem.
Hashem presented Avraham with a test that would try both aspects of his being at once. “Take your only son, whom you love.” When Avraham’s fatherly love was at its peak, he would be forced to show utter, unquestioning obedience to Hashem’s command – as unfathomable as it seemed. Thereby, he would prove his loyalty to the extent that Hashem personally testified, “For now I know that you fear G‑d, since you have not withheld your only son from Me.”
The Midrash relates that after the Akeidah, Avraham began to wonder what was the meaning of it all. First, Hashem promised him that Yitzchak would carry on his lineage. Then, Hashem ordered him to offer Yitzchak as a sacrifice. Finally, Hashem ordered him to stay his hand, and spare Yitzchak’s life. Hashem then explained that He had only intended for Yitzchak to be raised upon the Mizbei’ach, but He had never intended for him to be sacrificed.
Why did Avraham wait until after the Akeidah to question Hashem’s command? Why did he not ask these questions before taking his knife in hand to slaughter his son?
As long as Avraham had a responsibility to fulfill, he served Hashem in the capacity of a slave. No questions or challenges could be brooked. Hashem commanded him to offer Yitzchak as a sacrifice, and Avraham hastened to comply, paying no heed to any misgivings.
After Avraham was told to spare Yitzchak, he no longer had any obligation to fulfill. He now assumed the role of a loving son, who was welcome to ask and understand the depth of his Father’s wisdom.
וזכר לנו ה' אלקינו את הברית ואת החסד ואת השבועה אשר נשבעת לאברהם אבינו בהר המריה. ותראה לפניך עקדה שעקד אברהם אבינו את יצחק בנו על גבי המזבח, וכבש רחמיו לעשות רצונך בלבב שלם, כן יכבשו רחמיך את כעסך מעלינו, ובטובך הגדול ישוב חרון אפך מעמך ומעירך ומארצך ומנחלתך.
Remember for our sake the covenant, the kindness, and the oath that You swore to Avraham Avinu on Har HaMoriah. Let the memory of the Akeidah appear before You, when Avraham Avinu bound his son Yitzchak on the Mizbei’ach, and conquered his mercy to fulfill Your will with all his heart. So too, may Your mercy conquer Your anger towards us, and in Your great benevolence, withdraw Your fury from Your nation, Your city, Your land, and Your inheritance.
 Berachos 26b
 Tehillim 92
 Bereishis 31:42
 See Maharsha, Yevamos 64a
 Zohar, Parshas Yisro 88b
 Bereishis 46:2
 Megillah 29
 Tehillim 20:2
 Bereishis 22:11-12
 Yeshaya 33:8
 Rambam, Hilchos Teshuva 10:2
 Zohar, Parshas Behar
 Bereishis Rabbah 56:8
 From Rosh Hashana Mussaf