We fear that the merciless one might forget on the Day of Judgment, so we keep writing down our own mistakes while still in this world.

There is a delightful, tender irony at the heart of this couplet. While most people dread the Day of Reckoning and conceal their faults, the lover is terrified that his merciless beloved might simply overlook him and forget to mete out punishment. For the lover, even the beloved's wrath is a form of intimate attention, so he diligently keeps a ledger of his own transgressions to guarantee they aren't ignored when the final day arrives.