WARSAW, Poland—The heads of Russia’s Orthodox church and Poland’s Catholic church are to sign an appeal to their nations to forgive each other for past historical wrongs.

The signing in Warsaw Friday has been described by the churches as historical act of reconciliation between two nations that have feuded for centuries and whose ties are still marked by distrust.

The document is to be signed in Warsaw’s Royal Castle between Russia’s Patriarch Kirill and Polish Archbishop Jozef Michalik.

The ceremony, however, is being overshadowed by an expected verdict in Moscow later Friday for three female punk rockers. The members of the Pussy Riot band will learn whether they face years in prison for waging a political protest against President Vladimir Putin and the Orthodox church earlier this year in Moscow’s cathedral.