Kibud Av v'Eim
The Chayei Adam (67) writes, "Honoring parents means to honor them in your thoughts... You should consider your parents to be gedolim, from the most important people in the world. This is the primary obligation of honoring parents."
The Torah tells us that Yitzchak had that type of admiration for his father, Avraham. He held his father in the highest esteem, and he therefore tried to resemble his father in as many ways as he could.
The Torah (26:18) tells us, את ויחפר יצחק וישב פלישתים ויסתמום אביו אברהם בימי חפרו אשר המים בארות להן קרא אשר כשמות שמות להן ויקרא אברהם מות אחרי אביו, "Yitzchak dug anew the water springs that were dug in the days of his father, Avraham (which the Pelishtim sealed up after Avraham's death) and Yitzchak called the wells the names that his father called them."
Rabbeinu b'Chaya explains that he didn't change the names of the wells. He wanted to call the wells the names his father called them. "He did this to honor his father. If the Torah tells us about this, it is apparently counted as one of Yitzchak's merits. We should do the same for our parents. Yitzchak didn't even want to change the names that his father gave to the wells. Kal vachomer, we should follow our parents' good customs and ways."
Chayei Adam teaches that the primary factor of kibud av v'em is to honor one’s parents in his heart, and to consider them as the most important people in the world, even if others don't view them that way.
The Rabbeinu b'Chaya concludes, "Perhaps this is the reason Yitzchak's name wasn't changed, unlike the other avos." אברם was changed to אברהם; Yaakov became ישראל. Yitzchak's name remained the same. Yitzchak didn't want to change the names his father chose; therefore, his name remained the same, too.
Eisav also honored his father; however, the Yaaras Dvash (Yaaras Dvash pg.70) says that he honored him in action and speech, but he didn't honor Yitzchak in his heart. To prove this, consider that Eisav brought Yitzchak dog meat! As the Targum Yonoson (27:31) writes, "Hashem prevented Eisav from finding kosher game. So, he found a dog, killed it, made a meal from it, and brought it to his father. He said, 'Father, get up and eat from your son's game.'" He wouldn't have done that if he had honored his father in his heart.
