"I am no mercenary," Cesar told Portuguese radio station Renascenca on Wednesday.
"It is a very good contract. It will provide me and my family with great financial stability," the attacking midfielder said without giving details of his contract.
Cesar, 24, arrived at Benfica from Brazil's Corinthians in 2011 and although he was not always a first-team regular he played over 20 matches and scored important goals for the Lisbon club both at home and in the Champions League.
He won his first cap with Brazil in a friendly against Gabon in late 2011.
"There are two sides to the coin," he said. "It will be a much more tranquil life financially, but sports wise it will distance me from my objectives which are the national team, playing in Europe and the Champions League and be among the best clubs in the world."
Cesar has a sweet left foot and is a free-kick specialist.
"I am going to be well, my mother is going to be well and that is the most important thing," he said.