SB 10.32.18

bhajanty abhajato ye vai
 karuṇāḥ pitarau yathā
dharmo nirapavādo ’tra
 sauhṛdaṁ ca su-madhyamāḥ
Synonyms: 
bhajanti — they devotedly serve; abhajataḥ — with those who do not reciprocate with them; ye — those who; vai — indeed; karuṇāḥ — merciful; pitarau — parents; yathā — as; dharmaḥ — religious duty; nirapavādaḥ — faultless; atra — in this; sauhṛdam — friendship; ca — and; su-madhyamāḥ — O slender-waisted ones.
Translation: 
My dear slender-waisted gopīs, some people are genuinely merciful or, like parents, naturally affectionate. Such persons, who devotedly serve even those who fail to reciprocate with them, are following the true, faultless path of religion, and they are true well-wishers.