April 13 (UPI) — Following a lengthy hospital stay for a critical respiratory problem, Pope Francis greeted parishioners gathered for Sunday Mass in St. Peter’s Square.

“Happy Palm Sunday and Happy Holy Week,” the pontiff said following the ceremony as he waved to the throngs of congregants. He greeted the crowd for about 10 minutes from a wheelchair.

An estimated 4,000 people were gathered in St. Peter’s Square, according to Vatican News — the press arm of the Holy See. The new release from the Vatican said the pontiff “is limiting his exposure to the elements in order to continue recovery from his respiratory conditions.”

“Sisters and brothers, I thank you very much for your prayers,” Francis said while delivering the Angelus prayer Sunday.

“At this time of physical weakness, they help me to feel God’s closeness, compassion and tenderness even more. I, too, am praying for you, and I ask you to entrust all those who suffer to the Lord together with me.”

Francis, 88, is recovering from double pneumonia, which left him hospitalized and, at times, in critical condition on a mechanical ventilator, for 38 days.

He made his first public appearance a week ago while receiving supplemental oxygen via a nasal cannula. This week, there was no oxygen tube.

The pontiff’s Palm Sunday appearance came against the backdrop of an Israeli attack on a hospital in Gaza, which drew condemnation from Christians. Francis addressed conflict in war-torn countries, including “Palestine.”

A statement from the Israeli Defense Forces claimed the targeted attack took out a Gazan military “command and control center.”