Yoga Sutra 1.33 the mind is made clear by meditation

Sūtra I.33

The mind is made clear by meditation on friendliness towards the happy, compassion for the suffering, goodwill towards the virtuous, and disinterest in the sinful

How is the mind to be trained? Practice on one principle has been taught; what is the one principle which is to be the object of the practice? He says, meditation on friendliness towards the happy, compassion for the suffering, goodwill towards the virtuous, and disinterest in the sinful.

Friendliness is meditation on being a friend, one who rejoices in happiness when he sees it without anything like envy. So towards suffering, a kindly sympathy, and to the righteous he feels goodwill. It is added that he should practise disinterest in regard to the doings of the habitually sinful.

Practice of this all the time produces pure dharma, which does no injury to living beings; this dharma makes the mind clear. When it is clear, it attains steadiness in one-pointedness; the meaning is that by one-pointedness it is concentrated in samādhi, as the Gītā says, ‘The mind of the pure-hearted soon becomes steady’ (II.65).

(Opponent) Disinterest cannot produce dharma because it is not an action, so why is it included?

(Answer) If indifference were not mentioned, the mind would become engaged with those habitually sinful, and from the taint arising from dealings with them, it would not be fit for meditations on friendliness and the others. Disinterest is mentioned only in the context of steadying the mind so that there should be no a-dharma arising from casual dealings involving habitual sinners. The great thing here is steadiness of the mind.

When he has thus engaged his mind in meditation on one principle in this way, the mind will come to samādhi and no obstacles will then arise.