Pope Benedict XVI delivered an emotional last Sunday prayer in St Peter's Square, saying God had told him to devote himself to quiet contemplation, but assuring he would not "abandon" the Church.
The final days of his pontificate are being overshadowed by mounting scandal over two cardinals — one accused of covering up paedophile abusers and the other accused of "inappropriate acts" — set to to take part in the conclave to elect the next pontiff.
But tens of thousands of supporters turned out for Benedict's final Sunday prayers ahead of his formal resignation on Thursday, often interrupting him with their clapping, cheering and chanting.
"The Lord is calling me to climb the mountain, to dedicate myself even more to prayer and meditation. But this does not mean abandoning the Church," the pope said from the window of his residence in the Vatican, his voice breaking with emotion.
"If God is asking me to do this it is precisely so I can continue to serve with the same dedication and love as before but in a way that is more appropriate for my age and for my strength."
The 85-year-old leader of the world's 1.2 billion Catholics announced earlier this month he will be stepping down because he lacks the strength to carry on.
His shock resignation ends an eight-year reign dominated by the priest child sex abuse scandal and efforts to counter rising secularism in the West.
He thanked the crowd with a final unscripted call, telling them, "We will always be close!"