S. R. Faruqi:

In this ground, a verse of Sauda's is almost an exact counterpart of Mir's:

thaa bah javaanii fikr-o-taraddud ba((d az piirii paayaa chain
raat to kaa;Tii dukh sukh hii me;N .sub;h hu))ii aaraam kiyaa

[in youth, there was concern and anxiety; afterward, in old age, we found peace
we spent the night in ups and downs; when morning came, we rested]

Mir's verse is better [because of its verbal affinities and colloquial vocabulary]. Between 'youth' and 'night', and 'old age' and 'morning', the affinity is obvious. Because in youth the hair is black, and in old age white. Another point is that youth is generally construed as day, and old age is generally construed as evening or night. The poet has used them quite contrarily to this, through which a new pleasure has been created.

FWP:

SETS
MOTIFS == NIGHT/DAY; OPPOSITES
NAMES
TERMS == AFFINITY

SRF's point about the color-coding is exactly right: the imagery here completely reverses our expectations. And it does so with such an air of simplicity and obviousness that it takes a minute even to realize the reversal. The verse sounds matter-of-fact and neutral: the speaker is simply giving us a brief overview of his life, literally in the first line and in a clearly framed metaphor in the second line. The unusualness of it only hits us afterwards. This is a nice verse to reflect on as you grow older.

Compare Ghalib's G{78,7}.