This is probably not what you're looking for, but I went poking around As You Like It (since Rosalind and Celia are cousins) and got:

Sweet are the uses of adversity,
Which, like the toad, ugly and venomous,
Wears yet a precious jewel in his head.
And this our life, exempt from public haunt,
Finds tongues in trees, books in the running brooks,
Sermons in stones, and good in everything. (II.i.11-17)

(Unfortunately Celia and Rosalind are closer than you and your cousin.)

Also I searched "benediction" at Poetry Foundation and got this poem.