Leviticus 26:18 (also vv. 21, 24, 28)
If after all this you will not listen to me, I will punish you for your sins seven times over.
The punishments described in Leviticus 26 were a prediction of what would happen if the Israelites failed to follow the laws God had given them as a covenant, or contract, with them - namely the commands to love God, love others, not worship other gods and follow other basic moral principles (Dt 6:5, Lev 19:18, Ex 20:2-17). To break the covenant and incur punishment, the Israelites would have to be committing idolatry, murder, rape, theft, adultery, etc. These sins (and others) ultimately deserve hell. Therefore any earthly punishment they received would always be less than what they deserved, not more.
It should be noted that when God says he will punish the Israelites seven times over, it's after the Israelites had already been punished for their sins and had refused to change their ways (Lev 26:14-18). When one punishment didn't get their attention, God increased the level of punishment until it eventually caused them to realize the magnitude of their wrongs and remember God. When they did finally repent, God was ready to forgive them and keep his part of the covenant in spite of their breaking it (Lev 26:40-45).