Leviticus 26:25
And I will bring a sword upon you, that shall avenge the quarrel of my covenant: and when ye are gathered together within your cities, I will send the pestilence among you; and ye shall be delivered into the hand of the enemy. And I will bring a sword upon you, that shall avenge the quarrel of my covenant: and when ye are gathered together within your cities, I will send the pestilence among you; and ye shall be delivered into the hand of the enemy.
Leviticus 26:3-28 lays out the covenant terms, promising for obedience rain in season, fruitful land, safety in dwelling, and victory over foes, and threatening curses for disobedience. The chapter was given as a warning for later generations, that disregard of its requirements would replace blessing with hardship. In that reversal the land would fail to yield its produce, strength would be spent in vain, and God himself would act against the disobedient.
The punishment specified for breaking the covenant is a sword that avenges the quarrel of the covenant, pestilence sent even when gathered together within cities, and delivery into the hand of the enemy. That warning is not limited to ancient Israel but applies to people now. God's people must heed His message, and those who depart from Him face punishment and the loss of His favor.
The same covenant warning bears on the duty to care for a brother in need, calling for brotherly love and practical help to relieve a poor brother rather than leaving him unaided. Helpers are to remember that they themselves may face hardship and need like aid. It also applies to those who selfishly withhold their means from God's work, with God scattering what was entrusted to them through losses of property, livestock, or crops.