Attānaṃ ce tathā kayirā;
yathāññamanusāsati,
sudanto vata dametha.
Attā hi kira duddamo.

One should do what one teaches others to do;
if one would train others,
one should be well controlled oneself.
Difficult, indeed, is self-control.

Dhammapada 12.159
The Dhammapada: The Buddha’s Path of Wisdom, translated from Pāli by Acharya Buddharakkhita