kam kisū ko mīr kī mayyat kī hāth āʾī namāz
naʿsh par us be-sar-o-pā kī balā kaṡrat huʾī
1) to very few people did [a chance to share in] the funeral prayer for Mir come to hand
2) at the bier of that helpless/'headless-and-footless' one, there was a devastating crowd
For there to be a number of people around the corpse of a be-sar-o-pā person has an extraordinary 'ironic tension'. This theme too is entirely new-- that at the funeral procession of 'Mir' (= the lover) there was such a crowd that many people were not able to perform the namāz-e janāzā . Imam Ahmad ibn Hanbal always used to say, 'Between us and you are funeral processions'. The Imam's point was that there would be arrangements for a crowd at his funeral procession. The person at whose funeral procession there's the biggest crowd, would presumably have the highest rank. It's possible that Mir too might have had in mind this saying of Imam Ahmad's.
Then, be-sar-o-pā is used, by implication, for a lover ([according to the dictionary] nūr ul-luġhāt ). But it has several meanings: (1) without resources/equipment; (2) anxious and troubled; (3) wandering/wanderer; (4) unstable, neglected. The final meaning has no relevance here. But all the others are appropriate to the present verse.
Mir composed this theme in the first divan as well, and two times in Persian. From the first divan [{401,11}]:
ziyādah ḥad se thī tābūt-e mīr par kaṡrat
huʾā nah vaqt-e musāʿid namāz karne ko
[there were crowds beyond all limit at Mir's bier
there did not occur a favorable time for doing the namaz]
In Persian, one verse:
'There was such a crowd at Mir's bier
That many were not able to offer the funeral namaz.'
In Persian, another verse:
'Mir was slain, and alas, that because of the crowd of people
I didn't at all have a chance to offer the funeral namaz!'
The Persian verses are, as usual, limp [sust]. The Urdu verse is good, but in the present verse the theme is stronger.