Explanation:

Once

The President is an integral Part of Legislature. Parliament consists of Lok Sabha, Rajya Sabha, and the President. Any bill passed by the Parliament becomes Act only when the president gives assent to the bill. If the Bill is ordinary Bill (not a money bill) the President can return the Bill to Parliament for reconsideration however if Bill is passed again with or without amendments and is presented before President, he is bound to give his assent on such Bill.