Sita's immortality boon

Rama, thereupon, prayed them to grant him firm adherence to virtues and invincibility
in respect of all foes. And he also asked for the restoration to life of all those monkeys
that had been slain by the Rakshasas, and after Brahma had said--So be it, those monkeys, O king,
restored to life, rose up from the field of battle, and Sita too, of great good fortune, granted
unto Hanuman a boon, saying, 'Let thy life, O son, last as long as (the fame of) Rama's achievements! And, O Hanuman of yellow eyes, let celestial viands and drinks be ever available to thee through my grace!'

Vana Parva: Section 289