Ian Paisley's congregation stayed after church on Sunday to pray for the ailing 85-year-old.
Worshippers at the Martyrs' Memorial Free Presbyterian Church in Belfast remained after their morning service to pray for the man who was their minister until just a few weeks ago.
At the request of the Paisley family there have been no official updates from the Ulster Hospital in Dundonald on Dr. Paisley's illness. It is widely believed that he is suffering from a serious heart condition after being admitted to the hospital's intensive care unit over a week and a half ago.
Free Presbyterian minister, the Rev Alan Smylie, who led and preached at Sunday's worship service, told those present that Dr. Paisley was very seriously ill.
"His condition is still very serious in the hospital but we trust that you will continue to pray for him that the Lord's hand will be upon him. He is the great physician, the one who can touch and heal and restore," Smylie said.
"The family deeply appreciate the prayers of God's people here at Martyrs and of course the prayers of God's people everywhere at this time," he said.
The Newsletter in Belfast reported that during the service, the Rev. Smylie prayed: "We think of those who are in particular need; we think of Dr. Paisley today in his particular need. We thank thee, Oh God, that thou art the great physician and that thou hast ministered to him even throughout the past seven days.
"And Lord, we pray that thou would continue to do that, even as we pray this morning. Oh God, draw near to that sickroom, come alongside that sickbed and pour in that balm of healing if it is thy holy will to restore him and grant him strength because we know that thou art able to do it."