The company was such that the evening light made the night feel like the bright day of dawn.

This beautiful couplet describes a companionship that was absolutely perfect and unending. The 'sham-rabi' refers to the vibrant, beautiful evening, and 'sahar' is the gentle dawn. Mir Taqi Mir is telling us that the company they shared spanned the entire duration—from the glow of the evening right through to the breaking light of dawn. It speaks of a profound, uninterrupted connection that felt eternal.