Do you know what the text says (in Latin/Greek)? I'm not familiar enough with it to know off the top of my head what you're referring to. But this web page may help:
It is bordered by three couples of massive pilasters, with Corinthian pilaster strips. Above the pilasters are six arches (three on each side) which support the long trabeation under the barrel vault enhanced with late 18th-century coffers during the pontificate of Pope Pius VI.
On the trabeation which extends the whole length of the basilica is a Latin text in large black letters on a gold background. On the left, starting from the back it reads:
Ego rogavi pro te, o Petre, ut non deficiat fides tua: et tu aliquando converses confirma fraters tuos
("I have prayed for you Peter, that your faith may never fail; and you in turn must strengthen your brothers" Luke 22:32).
On the right, starting above the statue of St. Peter and extending to the back wall, are the words:
Quodcumque ligaveris super terram, erit ligatum etin coelis: et quodcumque solveris super terram, erit solutum et in coelis
("I will entrust to you the keys of the kingdom of heaven. Whatever you declare bound on earth shall be bound in heaven; and whatever you declare loosed on earth shall be loosed in heaven." Matthew 16:19).'
