Some 900,000 Poles sang, clapped and chanted "Benedetto, Benedetto" at Mass in a soggy field Sunday for Pope Benedict XVI, who urged them to share their faith with other countries in a mostly secular Europe.

Benedict said that was the best way to honor his predecessor, John Paul II — one of the themes of his four-day visit to John Paul's homeland.

"I ask you, finally, to share with the other peoples of Europe and the world the treasure of your faith, not least as a way of honoring the memory of your countryman, who, as the successor of St. Peter, did this with extraordinary power and effectiveness," said Benedict as he concluded his homily during the Mass in the Blonia meadow.

"I ask you to stand firm in your faith! Stand firm in your hope! Stand firm in your love! Amen!" he concluded, speaking in Polish on the last day of his trip.

The enormous, exuberant crowd chanted his name and sang "Sto Lat," or "A Hundred Years," wishing him a long life.

Benedict has appealed to dominantly Catholic Poland to serve as a beacon of faith in a Europe that has become mostly secular. The country joined the European Union only two years ago, 15 years after the collapse of communist rule.

"He told us that we should remain ourselves, that we should stay as we were before, attached to our traditions and Christian values," said Jacek Radon, a 37-year-old businessman from Krakow. "We should carry into the European Union our attachment to faith and to Christ."

"We should be ourselves, which means we should not take shortcuts to an easy and comfortable life with no responsibility, but should take responsibility and act according to our faith."

Later in the day, the pope is to make a somber stop at the Auschwitz-Birkenau concentration camp before flying back to Rome. The visit, by a German pope who was enrolled unwillingly in the Hitler Youth and drafted into the German army, is heavy with significance for Catholic-Jewish relations.

A shadow was cast over the Auschwitz visit by an attack Saturday on Poland's chief rabbi, Michael Schudrich, who is to say Kaddish, or the Jewish prayer for the dead, during the ceremony led by the pope.

Schudrich told The Associated Press that he was attacked in central Warsaw after confronting a man who shouted at him, "Poland for Poles." The rabbi said the unidentified man punched him in the chest and sprayed him with what appeared to be pepper spray, but that he was uninjured. Police said they were treating the incident as a possible anti-Semitic attack.

The 79-year-old Benedict has reached out to Poles by delivering parts of his speeches and homilies in Polish, and by retracing beloved native son John Paul II's steps. He visited John Paul's birthplace, Wadowice, and Sunday's Mass was held on the same spot where John Paul also drew large crowds on his return trips to Krakow, where he served as archbishop before becoming pope.

Although Benedict has avoided using German, some at the Mass held German flags and a banner reading in German, "We greet our Holy Father."

Benedict has won applause during his visit to Poland for encouraging prayers for John Paul's canonization, and for saying he hopes it will happen "in the near future."

People in Krakow have responded warmly, giving him his first John Paul-sized crowds of the trip, with police estimating Sunday's crowd at 900,000 — on the order of the throngs who turned out for John Paul, and more than the roughly 300,000 who came to Benedict's Mass on Thursday in Warsaw on the first day of his trip.

Some people spent the night in the field, while others streamed in with folding chairs and umbrellas early in the morning.

Kamila Wrobel, 16, spent the night in the meadow and got soaking wet, but felt it was worth it. She rode four hours with her Catholic youth group from the town of Debica, and was present for John Paul's Mass in the meadow in 2002.

"The pope is probably in Poland for the first and last time," she said. "This is a great, great experience filled with emotion.

"When he says something in Polish, then the atmosphere becomes really very special," she said.