Halakhah sur Malachie 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.