asanno ’pi viduravat
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
King Prthu was born of the dead body of King Vena as fire is produced from arani wood. Thus King Prthu will always remain just like fire, and his enemies will not be able to approach him. Indeed, he will be unbearable to his enemies, for although staying very near him, they will never be able to approach him but will have to remain as if far away. No one will be able to overcome the strength of King Prthu.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Arani wood is a kind of fuel used to ignite fire by friction. At the time of performing sacrifices, one can ignite a fire from arani wood. Although born of his dead father, King Prthu would still remain just like fire. Just as fire is not easily approached, King Prthu would be unapproachable by his enemies, even though they would appear to be very near him.