"Every Indian still regrets that he (Patel) did not become the first Prime Minister. Had he been the first Prime Minister, the country's destiny would have been different," he said in comments that may be seen as an attack on Nehru.
The BJP's prime ministerial candidate was speaking at a function to inaugurate a museum dedicated to Sardar Patel, who was born in Gujarat.
Invoking Patel, Modi said the first Home Minister was instrumental in uniting the country after Independence. "That unity and integrity of the country today is under threat from all fronts, be it terrorism or Maoism," he said, adding Singh himself had said that Maoism is a great threat to the country.
Referring to those who have resorted to terrorism and Maoism, Modi said they were causing the biggest harm to their own communities and appealed to the "misguided" youth to shun violence and return to the mainstream for the country's development.
Citing the example of Punjab, he asserted that those resorting to violence would not succeed in the country of Mahatma Gandhi and Patel.
"I want to tell the misguided youth who resort to bombs and guns that they cannot succeed in the land of Gandhi and Sardar (Patel). They cause harm to the country. But the biggest harm is caused to their own communities," he said.