She came at once, after saying pleasantly to Mr. Renfield, "Goodbye, and I hope I may see you often, under auspices pleasanter to yourself."
To which, to my astonishment, he replied, "Goodbye, my dear. I pray God I may never see your sweet face again. May He bless and keep you!"

– Bram Stoker

Dracula, Chapter 18. Renfield appears to have taken a shine to Mina and doesn’t wish to see her come to harm at the hands of Dracula. He knows that he is helping Dracula in his evil ways and seems to have some regrets about this. So he prays to God that he will never see Mina’s sweet face again – he wants her protected from the dark events that are to come. This foreshadows the special interest that Dracula will take in Mina, when he later subjects her to a number of attacks, including a particularly horrific one.