S. R. Faruqi:

In order to understand with what perfect appropriateness the idiom has been used here, imagine that as yet the poet has composed only the first line. The thought is complete, but the verse has not become complete. It was necessary for some metaphor or simile to be brought, for the speaker's wretched condition.

But the poet's creative mind searched out an idiom that is suitable in the dictionary sense, and is perfect in the metaphorical meaning too. When the beloved is far away, how wretched our condition is-- only we can know this, and it's not possible for this to be as clear to anyone else as it is to us.

Hali too has taken good advantage of this idiom:

ho ((azm-e der shaayad ka((be se phir kar apnaa
aataa hai duur hii se ham ko na:zar ghar apnaa

[perhaps it might be a longstanding resolve, our turning back from the Ka'bah
only/emphatically from far away, we see our home]

FWP:

SETS
MOTIFS == HOME
NAMES
TERMS == IDIOM; OPENING-VERSE

This ghazal begins with two opening-verses; of these, SRF has chosen only the second for inclusion in SSA.

The idiom itself is somehow very moving, with its equal emphasis on the longed-for sight of home, and the misery of seeing it from a hopelessly long distance away. Combining the vision of home as the nearest thing to the heart, the most desirable thing in the world, with the painful idea of seeing home from a distance, creates a powerful back-and-forth tension.

Does one want to weep with joy at the sight of home, or with sorrow at its remoteness? And of course, since it's really impossible to see one's home from such a distance, the whole experience is a kind of dream or imaginative vision anyway, so the emotional valences are all the more potent.

Note for translation fans: A kos is more like two miles than one, so it would be more literal to convert the distance to 'two hundred miles'. But of course, then the resonance of 'a hundred miles' ('You can hear the whistle blow a hundred miles...') would be lost, which would be especially a pity since it's in the context of a proverb. A kos is about a 'league' (as in 'Half a league, half a league, half a league onward'), but younger readers may not even know what a league is. Alternatively, one could keep 'a hundred kos ', but that too sacrifices the idiomatic feeling in English, and how much good does it do? In this case, does it matter exactly how far the (purely notional) distance is? The translator has to make hundreds of such choices, and it's smart to make them carefully and thoughtfully, and preferably as consistently as possible within each text. And even more preferably, with an introduction that explains how and why you've made the kind of choices that you've made.