Pakistan will play the traditional Boxing Day and New Year Test matches.
He got married during the ODI and T20I series against Sri Lanka last year and was also rested for the Nidahas Trophy.
"I am humbled to have been selected for such a noble cause," Afridi said.
"For the next few months, I am not keen on bowling," Mathews said.
Sri Lanka is set to tour West Indies in the last week of May for three-match Test series.
The former Sri Lanka off-spinner was perhaps the best bowler of all time.
Minister of Urban Development, Water Supply and Drainage of Sri Lanka Abdul Rauff Hibbathul Hakim appreciated the plan of having green matches.
Winning a Test series after coming from behind always makes it an absorbing affair and out of 40 such instances where a team has won a series after trailing in the history of the game, we pick the top five.
The tour will commence on July 12.
The southpaw was in full flow in the recently-concluded Nidahas Trophy 2018.