SB 4.16.16
drdha-vratah satya-sandho
brahmanyo vrddha-sevakah
saranyah sarva-bhutanam
manado dina-vatsalah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The King will be firmly determined and always situated in truth. He will be a lover of the brahminical culture and will render all service to old men and give shelter to all surrendered souls. Giving respect to all, he will always be merciful to the poor and innocent.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The word vrddha-sevakah is very significant. Vrddha means “old men.” There are two kinds of old men: one is old by age, and another is old by knowledge. This Sanskrit word indicates that one can be older by the advancement of knowledge. King Prthu was very respectful to the brahmanas, and he protected them. He also protected persons advanced in age. Whatever the King would decide to do, no one would be able to stop. That is called drdha-sankalpa, or drdha-vrata.