Sudama was a garland-maker who offered Krsna many nice garlands, sandalwood and other things. He used to go to Vrindavan regularly to collect flowers, so he had already met Krsna and made offerings, and was recognised by Krsna as a devotee.
Once he adorned Krsna with a beautiful garland, and Krsna and Balaram looked very nice. Then the two Lords offered the surrendered Sudama, who was bowing down before them, whatever benediction he desired.
Then Sudama asked the Lord for unshakeable devotion – devotion that could not be destroyed by anything. He also asked for friendship with the devotees and for transcendental compassion for all living entities.