Malaquías 3:4 Halajá: Mishneh Torah, Repentance & Kitzur Shulchan Arukh

How superior is the degree of repentance! But yesterday was this sinner separated from the Lord God of Israel, even as it is said:" But your iniquities have separated between you and your God" (Is. 59.2); cries, but received no answer, even as it is said:" "Yea, when ye make many prayers, I will not hear" (Ibid. 1.15); does obey commandments, but they are thrown back in his face, even as it is said: "Who hath required this at your hand, to trample My courts"? (Ibid.–12), and, "Oh that there were even among you that would shut the doors, that ye might not kindle fire on Mine altar in vain!" (Mal. 1.10). But to-day he is connected with the Shekinah, even as it is said: "But ye that did cleave unto the Lord your God are alive every one of you this day" (Deut. 4.4); he cries and receives answer momentarily, even as it is said: "And it shall come to pass that before they call, I will answer" (Is. 65.24); he observes commandments, and they are received with pleasure and joy, even as it is said: "For God hath already accepted thy works" (Ecc. 9.7); moreover, his works are pleasurably anticipated, even as it is said: "Then shall the offering of Judah and Jerusalem be pleasant unto the Lord, as in the days of old, and as in ancient years" (Mal. 3.4).

It is customary to read the Haftarah from Malachi 3:4, Ve'arvah etc. because it is written there, "Bring all the tithes into the storehouse etc." That is appropriate for the day, for (according to some authorities), the time at which all tithes had to be removed from the house was on erev Pesach of the fourth year of the Shemitah cycle, and on erev Pesach of the seventh year of the Shemitah cycle. All the tithes which were separated from your grain during the three years, and which were kept in your house, had to be given to the Levi at the above-mentioned times.