0106 GMT October 15, 2019
The nationalist leader compared voting to Hindus cleansing their sins by bathing in the Ganges River after he cast his ballot in his home state of Gujarat, AFP reported.
The 117 seats over 15 states being fought for on Tuesday were the biggest number of any of the seven stages of voting over six weeks.
While Modi's right wing Bharatiya Janata Party (BJP) is considered the frontrunner in the vote, it faces a tough challenge from the opposition Congress party of Rahul Gandhi.
Modi, who ruled the western state for over a decade before leading his party to national power in 2014, has stressed at rallies the need for the 900 million electorate to turn out.
"By voting, I feel the same sense of purity that one gets by taking bath at the Kumbh festival," he said, referring to the mass bathing by Hindus in the Ganges.
Modi has made national security and fighting terrorism his main campaign theme to blunt opposition attacks on his handling of the economy.
Gujarat sends 26 lawmakers to the Parliament and the right-wing BJP won all of those seats in 2014.
Modi voted in the constituency where his close associate Amit Shah, the BJP president and key powerbroker, is contesting his maiden election.
Gandhi is standing in Wayanad in Kerala state, taking a risk as south India is considered a stronghold of regional parties.
Under Indian election law, candidates can contest two seats, though they can only keep one if they win both. Gandhi is also on the ballot for Amethi in Uttar Pradesh.
Round three of seven
Turnout was robust in the first two rounds of voting, on April 11 and 18, with around 70 percent of eligible voters taking part.
Heavy security were put in place for voting, though violence has still been reported, with Maoist rebels carrying out bomb and shooting attacks.
Media reports said suspected Maoists detonated an improvised explosive device in eastern Jharkhand state on Tuesday without causing any damage.
Election results are to be released on May 23.
The fractured opposition, led by Congress, has sought to attack the government over employment, the economy and a debt crisis for Indian farmers.