Lalu Yadav, jailed in Jharkhand's Ranchi after being convicted in a fodder scam case, had been released on Thursday on three-day parole for his son Tej Pratap Yadav's wedding.
"I congratulated Lalu Ji on being granted bail for six weeks and asked him to take proper care of himself by doing yoga," said Ramdev, revealing his advice to the former Bihar chief minister.
Lalu Yadav, 69, has spent weeks in hospital over multiple health problems and was recently discharged from the AIIMS hospital in Delhi against his wishes.
"It will add beauty to your face. We make Ayurvedic products, foreign companies use chemicals," said the yoga guru, proceeding to feed the 67-year-old politician an energy bar.
In the past, Lalu Yadav has poked fun at Ramdev - who is seen to be close to the BJP - and said: "Ramdev said he will do yogasan in Ramlila Maidan. When the police came, he did kudasan (jumped)" - a reference to the yoga teacher jumping off the stage when the police cracked down on his protest in 2011.
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