Musar for Berakhot 121:27

But the counsel of the yetzer is known in this, that when a mitzvah of this kind presents itself to him he assumes a cloak of humility, saying: "I am the least of [those in] the city, and my words will certainly not be heeded. Why should I waste my breath?" But when a man reflects upon himself, he will see that this is only the counsel of the yetzer. For if, in the midst of his speaking, someone would in the least "touch" his honor, his mouth would "sling torches" at him, and he would arouse men to defend him against the other. But when the honor of G-d is at stake, he suddenly becomes humble and lowly. This is nothing other than the yetzer hara changing the man, as the leopard, its spots. [This is what Chazal (Berachoth 61a) intimated (in saying) that the yetzer hara lies between the two chambers of the heart, having no fixed place, as the yetzer tov does, to the right. But he varies his enticements, all according to the situation.]

The mention of the "garment" in this story is an allusion to the "leather garments." Ever since man became degraded, so that he needs to wear these kinds of garments, he has also become a target for the evil urge to focus upon.

And it is known that it is the way of the yetzer to vary its stratagems, for which reason it sits at the two openings of the heart (Berachoth 61a). That is, sometimes it instills pride into a man's heart to make him think that he is one of the fearers of the L-rd, and perhaps, even one of his lovers. And when it beholds a man who wishes to strengthen himself in something for the honor of the Blessed L-rd, in the manner of a true lover, it casts sadness upon his heart, so that he thinks that this mitzvah or this mode of conduct does not become him, but only "the holy ones who are in the land," not one so small as he. And it reawakens in his thoughts mean acts that he did in the days of his youth. And even though sometimes he regrets and is embittered over this, it causes him to forget this and to remember only things that suit his situation, as he thinks, in order to vex and humble him so that he will have no desire for that mitzvah.