All his life Peter fasted on Saturday in honour of Our Lady, and strongly recommended this practice to his religious.
When returning home, a great storm arose in the Adriatic and the ship was in imminent danger of destruction; Peter made a vow to build a church in honour of Our Lady should he safely reach the harbour.
In fulfilment of his promise, in 1096 he built a church and the monastery of Santa Maria in Portofuori on the family property.
Nearby there was a small community of clerics, and Peter having joined them, was soon after made their superior, and with them removed to the church and monastery he had built, in 1099.
These were approved by Pope Paschal II in 1116, and having afterwards been adopted by many other communities of Canons Regular, the Portuensis Congregation was formed.