The Archbishop was Thomas Secker.
So far I can't be quite sure which church Thomas visited but it seems likely to be St Mary's Lambeth
It's now the Museum of Garden History (John Tradescant and his son who were famous plant collectors were buried in the churchyard which makes that appropriate).
The text is hardly clearly stated, but I think it must be Luke chapter 12 v5-7. What is certain is the version which will have been in use - the King James. So those verses in that translation read.
"But I will forewarn you whom ye shall fear: Fear him, which after he hath killed hath power to cast into hell; yea, I say unto you, Fear him.
Are not five sparrows sold for two farthings, and not one of them is forgotten before God?
But even the very hairs of your head are all numbered. Fear not therefore: ye are of more value than many sparrows."