Mischna zu Dewarim 14:28

Wild beasts come to the world for swearing in vain, and for the profanation of the Name. Exile comes to the world for idolatry, for sexual sins and for bloodshed, and for [transgressing the commandment of] the [year of the] release of the land. At four times pestilence increases: in the fourth year, in the seventh year and at the conclusion of the seventh year, and at the conclusion of the Feast [of Tabernacles] in every year. In the fourth year, on account of the tithe of the poor which is due in the third year. In the seventh year, on account of the tithe of the poor which is due in the sixth year; At the conclusion of the seventh year, on account of the produce of the seventh year; And at the conclusion of the Feast [of Tabernacles] in every year, for robbing the gifts to the poor.