SB 5.4.6
yasya ha pandaveya slokav udaharanti —
ko nu tat karma rajarser
nabher anv acaret puman
apatyatam agad yasya
harih suddhena karmana
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O Maharaja Pariksit, to glorify Maharaja Nabhi the old sages composed two verses. One of them is this: “Who can attain the perfection of Maharaja Nabhi? Who can attain his activities? Because of his devotional service, the Supreme Personality of Godhead agreed to become his son.”
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The words suddhena karmana are significant in this verse. If work is not carried out in devotional service, it is contaminated by the modes of material nature. That is explained in Bhagavad-gita: yajñarthat karmano ’nyatra loko ’yam karma-bandhanah. Activities performed only for the satisfaction of the Supreme Lord are pure and are not contaminated by the modes of material nature. All other activities are contaminated by the modes of ignorance and passion, as well as goodness. All material activities meant for satisfying the senses are contaminated, and Maharaja Nabhi did not perform anything contaminated. He simply executed his transcendental activities even when performing yajña. Consequently he obtained the Supreme Lord as his son.