إذا شابَ العاقِلُ شَبَّ عَقلُهُ، إذا شابَ الجاهِلُ شَبَّ جَهلُهُ.
Imam Ali (as):
When an intelligent man grows old, his intellect remains young [and sharp], and when an ignorant man grows old, his ignorance too remains young [and more reckless].
Source:
Ghurar al-Ḥikam
No4169
ID: 1033