Musar על ישעיהו 1:15

Modesty is indeed a good quality and is the opposite of arrogance. And he who possesses this quality has already turned away his soul from all sorts of evils, and he who has reached this honored lofty degree performs a precept and receives his reward according to the greatness of his humility. For Modesty is the root of Service to God, and a small deed done with Modesty is received by God, Blessed be He, a thousand times more readily than a great deed performed with arrogance. And thus did our Sages say: "The one who sacrifices much and the one who sacrifices little have the same merit, provided that the heart is directed to heaven" (Berakoth 5b Menahoth, 110:a). But a work done with arrogance is not welcomed by God, Blessed be He, for it is an abomination to His Spirit, as it is said: "Every one that is proud in heart is an abomination to the Lord" (Proverbs 16:5). "And because of this he cries and is not answered, as it is said: "Yea, when ye make many prayers I will not hear" (Isaiah 1:15). And a man of arrogance may perform the precepts and they tear them to pieces before his eyes, as it is said: "Oh, that there were even one among you that would shut the doors (of the Temple so that the arrogant would not presume to serve Me!)" (Mal. 1:10). And when an arrogant person brings a sacrifice it is not received, as it is said: "Who hath required this at your hands, to trample My courts?" (Is. 1:12). And, it is said: "Add your burnt offerings unto your sacrifices and eat ye flesh" (Jer. 7:21). (That is to say. "Don't offer your burnt offerings to Me; I do not want them.")

And what really is modesty? It is humility and lowliness of the spirit, regarding oneself as nothing. And a man must feel this constantly — to be low in his own eyes, humble of soul, tender of heart, and broken in spirit. The root of modesty is that he shall consider, while he is at peace and quiet, healthy and rich, that the Creator, Blessed be He, has done much good to him, and that he is undeserving of all that God has given him. And he should think about the greatness of God and the exaltation of His glory, and should consider, "What am I? Am I not a small humble creature and I am in a lowly transitory world." And he should further think, "All the good deeds that I am able to do are nothing but a drop in the ocean in contrast with what I ought to do." And he must do all of his deeds for the honor of Heaven, and not to flatter any man, or for the sake of pleasure, but he must do everything for the sake of God's Great Name. This is the root of modesty

Know that anyone who wishes to know if his God is pleased with him should weigh within himself, as we have said, his merits and deficiencies. If he sees that he inclines to evil lusts and the pursuit of wealth, the lust of women, immoral profit, robbery, and pleasures more than he inclines to the service of God and to prayer, charity, and good deeds, let him know that he is wicked and that God does not accept his actions. But if he inclines to good deeds more than he inclines to things which are bad, let him know that he has been noted for good. If a man wishes to do a worthy deed or fulfill a commandment, and this deed happens to be close at hand and nothing restrains him from doing this deed, then let him know that he has found favor in the eyes of his God. But if he sees that when he wishes to do a sinful thing, nothing happens to interfere or restrain him, and that when he wishes to do a worthy deed or observe a commandment, there are certain things which do interfere and restrain him, let him know that the Creator rejects him and does not love his deeds. It is said (Isaiah 1:15), “And when you spread forth your hands, I will hide Mine eyes from you.”