The 29-year-old earns around €1million-per-season for three years at the Russian club and Navas says that is the reason for his switch.
“It was an irresistible offer that I could not turn down,” he told AS.
“Everything was agreed and at my age I have assured mine and my family’s future financially by signing this contract.
“I know that some people say that footballers only think about money and that I am a mercenary, but I think nearly everyone would have done what I have done.
“I do not know anything about the city and I do not know much about the team, but I have been told good things.”