Musar for Megillah 55:15

The commandment to rejoice on the festivals and to make the pilgrimages to Jerusalem on the respective festivals of פסח, שבועות, סוכות, applies to every male Israelite. Our sages (Chagigah 2a) have said: כדרך שבא לראות כך בא ליראות, "Just as a person comes to ‘see,’ so he is seen." If he wants to be seen in the Holy Temple, in the residence of G–d's glory, then he first must fulfill סור מרע ועשה טוב, "Abandon evil and do good" (Psalms 34,15). How could one failing to comply have the effrontery to show himself to G–d and offer total offerings and festival offerings? As a sinner he is even forbidden to show himself i.e. to look upon the faces of רשעים! Having mended his ways, however, he himself becomes the sacrifice by means of the offering he has brought in the Temple.

שלוש פעמים בשנה יראה כל זכורך וכו. Rabbi Menachem Habavli explains that ordinarily a person who is full of sins (as we all are) would not have the audacity to appear before His King three times a year wearing these sins around his neck as if they were jewelry. Since we are commanded to make such appearance, it is clear we must see to it that we are free from sin. The word פעמים is reminiscent of פעמון ,bell. In other words, the commandments are to serve as an alarm bell that we should cleanse ourselves from sin before undertaking the pilgrimage and appearing in the Presence of G'd in the holy Temple.

The righteous people reject the wicked, and our Sages, of blessed memory said, "Not for nothing did the starling follow the raven, but because it is of the same kind" (Baba Kamma 92b). And it is said, "Every fowl dwells near its kind and man near his equal" (Ben Sira 13:5). And they said, "It is forbidden to look at the form of a wicked man" (Megillah 28a), as it is said, "Were it not that I regard the presence of Jehoshaphat the king of Judah, I would not look toward thee, nor see thee" (II Kings 3:14). And everyone who looks at the form of a wicked man, his eyes grow dim in his old age, like Isaac, our father, whose eyes grew dim because he looked upon Esau, even though he did not know of Esau's evil deeds.

אל תפנו אל האובות ואל הידעונים . "Do not turn to ghosts and do not inquire of familiar spirits." The reason is that such ghosts are apt to turn you away from having faith in G–d who is the Creator of all. The method employed by people who are experts in communicating with the dead involve manipulating the powers of impurity. When these "dead" spirits make predictions of the future some will come true, others will not. The reason the Torah calls these ghosts אבות, "fathers," is that they are the "patriarchs" of all the forces of impurity. The Torah says "do not turn to them" instead of "do not practice or perform such rites" so that you should not even contemplate having anything to do with such practices. The word תפנו is related to פנים, face. Merely looking at such ghosts introduces impurity into the atmosphere; it is just as damaging as looking at the face of a wicked person.