הלכה אויף מלאכי 3:10

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.

“Bring ye the whole tithe into the storehouse etc.… And try Me now herewith” (Mal. 3:10). So important is tithing, that here the Holy One, blessed be He, said, “Try Me,” unlike all other instances where it is forbidden to test Him, for it is written “Ye shall not try the Lord your God” (Deut. 6:16).¹Taanith 9a. That tithe alluded to is the poor man’s tithe, to give to the poor a tithe from everything wherein a person profits, whether from interest or his own hire or from anything which comes to a person profitably. If he found or they returned to him goods stolen from him,²Valuables that he had given up for lost. he must tithe, as it is written in Scripture.³The words “whole tithe” is taken to imply all sorts of revenue accruing from all sources, foreseen and unforeseen. (Perush.) For Israel had not yet been among the nations of the world lending at interest.⁴The Bible does not mention income from interest since it was then not prevalent. Woe unto them that withhold their tithes, for ultimately nothing will remain in their hands but the poor man’s tithe, as it is written, “And everyman’s hallowed things shall be his” (Num. 5:10).⁵Berakoth 63a.

Charity prevents threatened punishment from Heaven, and in famine it delivereth from death, as in the story of the widow of Zarephath.¹I Kings 17.