The Bhagavad Gita · Chapter 3 · verse 3.21
Whatever a great person does, others follow. Whatever standard they set, the world pursues.
Sanskrit (Devanagari)
यद्यदाचरति श्रेष्ठस्तत्तदेवेतरो जनः। स यत्प्रमाणं कुरुते लोकस्तदनुवर्तते॥
Transliteration
yad yad ācarati śreṣṭhas tat tad evetaro janaḥ; sa yat pramāṇaṁ kurute lokas tad anuvartate
English translation
Whatever a great person does, others follow. Whatever standard they set, the world pursues.
Meaning, what the verse is actually saying
Leadership is by demonstration, not declaration. People absorb behaviour they observe more reliably than instruction they receive. If you have any role of influence — parent, teacher, manager, founder — what you do quietly is your real curriculum.
Modern practice, what to do today because of this
Before correcting someone you have influence over, ask: am I demonstrating, in my own behaviour, what I am asking them to do? If no, fix that first. The correction without the demonstration teaches the opposite of what it intends.