“Self-discipline leads to freedom.”
This isn't one of Bhartrihari's verses. It is an idea from commentary on them. For his own words, see the verses we've referenced.
About the poet: Bhartrihari
Bhartrihari is the Sanskrit poet to whom the Shatakatraya is attributed: three collections of about 100 verses each, usually dated to around the 5th century CE. They cover worldly conduct (Niti), love (Shringara) and renunciation (Vairagya), often in a wry, sceptical voice.