Buddhist Dhammapadha Age is not the criterion

Chapter XIX - DHAMMATTHA VAGGA - The Just or Righteous

GREY HAIR ALONE MAKES NOT A THERA

GREY HAIR ALONE MAKES NOT A THERA

Na tena thero hoti yen' assa palitam siro
Paripakko vayo tassa mogha jinno' ti vuccati. [260]

HE IS A THERA WHO IS STAINLESS

Yamhi saccan ca dhammo ca ahimsa sannamo damo
Sa ve vanta malo dhiro thero iti pavuccati. [261]

He is not thereby an Elder (Thera) ¹merely because his head is grey.
He who is ripe only in years is called 'one grown old in vain'. [260]

Only a wise man who comprehends the Four Noble Truths and the Dhamma, who is harmless and virtuous, who restrains his senses and has rid himself of moral defilements is indeed called a Thera. [261]

XIX: 04 Age is not the criterion

One day, a group of bhikkhus came to pay respects to the Buddha. He knew that the time was ripe for those bhikkhus to attain Arahanthood. So he asked them whether they had seen a certain Elder as they came into the room. They replied that they did not see any such Elder but they only saw a young novice monk. Whereupon, the Buddha said, 'Bhikkhus! That person is not a novice monk. He is an Elder. I don't call one an Elder just because he is old. An Elder is one who comprehends the Four Noble Truths and does not harm others.'

Notes:

Thera — a term applied to those bhikkhus who have counted at least ten years in the Order from the date of their higher ordination. Thera, literally, means one who is firm or stable.