Why can't Argentina retire Lionel Messi’s iconic number 10 jersey?

Argentina cannot permanently retire Lionel Messi’s iconic number 10 jersey because FIFA regulations require squads to use shirt numbers 1 to 26 during FIFA and confederation tournaments. Argentine Football Association had also tried to retire Diego Maradona’s number 10 jersey, but FIFA rejected the move. Argentina can, however, leave Messi's number unused in selected friendlies after his farewell.