Thirukkural-On Virtue-On Fate-Kural 378

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The poor, without many worldly possessions, will surely resort to satisfying renunciation,
If ordaining fate will spare them their share of pain and grief.

The idea is that normally it should be easy for those who have no possessions or stakes of their own, to give up the world, but they also do not renounce and prefer to struggle and wallow in their misery, caused principally by worldly attachments. This is because they have not earned the right kind of disposition for renunciation by their previous good deeds.

Obviously, Valluvar considers this situation as the proof for his belief that Karma from previous birth does regulate one"s nature and tendencies, as otherwise, why should a poor man, who has so very little to renounce, not throw it all up instead of continuing to flounder in the filth and vice of this misery.