As far as the great devotees of the Lord are concerned, they can purify a degraded soul just by being them and what to speak of the benefits of their association.
Dhritarashtra was lucky enough to have a brother whose very association was a source of liberation for his frustrated life.
Stabilization of renunciation is possible only by association with bona fide saints and self-realized souls by which one can be engaged in the loving devotional service of the Lord.
By associating with pure devotees and by hearing them submissively, attachment for material enjoyment becomes slackened and attraction for hearing about the transcendental activities of the Lord becomes prominent.
By association with pure devotees one is gradually promoted to his transcendental consciousness.
The intelligent, who have understood the Supreme Lord in association with pure devotees and have become freed from bad materialistic association, can never avoid hearing the glories of the Lord, even though they have heard them only once.