Council of Chalcedon
Council of Chalcedon, Canon XI
Definition of faith and received canons; reception qualifications retained; not the full proceedings
Canon XI
We have decreed that the poor and those needing assistance shall travel, after examination, with letters merely pacifical from the church, and not with letters commendatory, inasmuch as letters commendatory ought to be given only to persons who are open to suspicion.
Translation: Henry R. Percival, The Seven Ecumenical Councils, NPNF II.14 (1900), via CCEL.
Source: Council of Chalcedon (CCEL)