Quote 1
"O, sir," cried Poole, "do you think I do not know my master after twenty years? Do you think I do not know where his head comes to in the cabinet door, where I saw him every morning of my life? No, sir, that thing in the mask was never Dr. Jekyll—God knows what it was, but it was never Dr. Jekyll; and it is the belief of my heart that there was murder done." (8.43)
Poole’s steadfast loyalty to Dr. Jekyll is borne out of twenty years of being his servant, not out of being his friend.
Quote 2
"Well, sir," he said, "here we are, and God grant there be nothing wrong."
"Amen, Poole," said the lawyer. (8.15)
As in many other places in the text, God is invoked in a plea.
Quote 3
"Changed? Well, yes, I think so," said the butler. "Have I been twenty years in this man's house, to be deceived about his voice? No, sir; master's made away with; he was made away with eight days ago, when we heard him cry out upon the name of God; and who's in there instead of him, and why it stays there, is a thing that cries to Heaven, Mr. Utterson!" (8.31)
Dr. Jekyll (who presumably is inside the laboratory) is in such depths of despair that he believes only God can aid him.