Dhamma Verses (Dhammapada, KN 2)

12: The Chapter about the Self – 154
Only the wise should advise
Ven. Upananda preached well but was a greedy monk who
always took the biggest offering, one day he swindled two
monks out of a blanket, and the Buddha explained that one
should train oneself before preaching to others, and
summarised his teaching with this verse.
158. Attānam-eva paṭhamaṁ patirūpe nivesaye,
athaññam-anusāseyya, na kilisseyya paṇḍito.
First one should establish oneself
in what is suitable, then one
can advise another, the wise one
should not have any defilement.