"The mandate is to serve the people and not to profit. The people's court is the biggest court and it is my duty to serve them. I can't serve one family," Mr Kumar said in searing attack on Lalu Yadav and his family, who he dumped two days ago over corruption charges against them.
He won the trust vote comfortably with 131 votes against the opposition's 108.
"People should not teach me lessons on secularism. Secularism is something that can be practised. I cannot be with such people who indulge in committing sins besides amassing property through corrupt means in the garb of secularism," Mr Kumar said in a dig at Mr Yadav, chief of the Rashtriya Janata Dal or RJD. But the jibe also appeared to aim for the Congress which has frequently countered BJP's charges of presiding over some of independent India's biggest corruption scandals by accusing it of undermining the country's inclusive constitution.
"I asked him (Tejashwi, Lalu Yadav's son) to explain the accusations of graft against him but he was not in a position to furnish reply", he said.
Mr Kumar had broken away from the 'Mahagatbandhan' or Grand Alliance on Wednesday, snapping ties with the Congress and RJD. He was sworn-in back to power yesterday after his estranged partner BJP decided to back him up. The falling-out stemmed from corruption charges that had circled Mr Yadav and his family.
"I took the decision in the best interest of Bihar and its development.... Now there is the rule of the NDA both at the Centre and in Bihar and the state will touch new heights of development," Mr Kumar said today.