imam baraylawi writes: hajar e aswad e ka'aba e jaan o dil ya'ani mohr e nubuwwat pe lakhoN salam --- at first glance, this couplet is about the black stone in the ka'aba. but, from the second line, we know it is about the seal of prophethood [mohr e nubuwwat]. alaHazrat describes it as the hajar e aswad and the ka'aba of our hearts and souls.