According to the Vedic system, one within the institution of varṇa and āśrama must leave his family life after he reaches fifty years of age (pañcāśad ūrdhvaṁ vanaṁ vrajet). Thus Sudyumna followed the prescribed regulations of varṇāśrama by leaving the kingdom and going to the forest to complete his spiritual life.
When the time was ripe, when Sudyumna, the king of the world, was sufficiently old, he delivered the entire kingdom to his son Pururava and entered the forest
Expressions researched:
"Thereafter, when the time was ripe, when Sudyumna, the king of the world, was sufficiently old, he delivered the entire kingdom to his son Purūravā and entered the forest"
Srimad-Bhagavatam
SB Canto 9
Thereafter, when the time was ripe, when Sudyumna, the king of the world, was sufficiently old, he delivered the entire kingdom to his son Purūravā and entered the forest.
Thereafter, when the time was ripe, when Sudyumna, the king of the world, was sufficiently old, he delivered the entire kingdom to his son Purūravā and entered the forest.