O Mir, you have failed to keep your promise; otherwise, I would have sworn upon my heart.

This couplet is a dramatic confrontation, a powerful accusation woven into poetry. The speaker is challenging Mir Taqi Mir, saying that the fault lies entirely with him for breaking a solemn promise ('badd-ahad'). The speaker implies that if Mir had not failed, the speaker would have kept their heart, or perhaps given it, based on the terms of that oath. It's a masterful display of poetic justice, where the poet turns the accusation back on the beloved.