jato ’yam kantaka-drumah
visnor nalayito ’rbhakah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
This rascal Prahlada has appeared like a thorn tree in a forest of sandalwood. To cut down sandalwood trees, an axe is needed, and the wood of the thorn tree is very suitable for the handle of such an axe. Lord Visnu is the axe for cutting down the sandalwood forest of the family of demons, and this Prahlada is the handle for that axe.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Thorn trees generally grow in deserted places, not in sandalwood forests, but the seminal brahmanas Sanda and Amarka compared the dynasty of the Daitya Hiranyakasipu to a sandalwood forest and compared Prahlada Maharaja to a hard, strong thorn tree that could provide the handle of an axe. They compared Lord Visnu to the axe itself. An axe alone cannot cut a thorn tree; it needs a handle, which may be made of the wood of a thorn tree. Thus the thorn tree of demoniac civilization can be cut to pieces by the axe of visnu-bhakti, devotional service to Lord Krsna. Some of the members of the demoniac civilization, like Prahlada Maharaja, may become the handle for the axe, to assist Lord Visnu, and thus the entire forest of demoniac civilization can be cut to pieces.