There is a quotation that rests in As You Like It about Rosalind; it ends with "so fair as Rosalind..." I can't sleep until I find out! It's probably by Jaques or Orlando.
Ok, I might be blind, but I can't find that reference anywhere in As You Like It.
This is the best I could come up with. Orlando writes it on a paper, in Act 3, Scene 2 and Rosalind picks up the paper and reads it:
From the east to western Ind,
No jewel is like Rosalind.
Her worth, being mounted on the wind,
Through all the world bears Rosalind.
All the pictures fairest lin'd
Are but black to Rosalind.
Let no face be kept in mind
But the fair of Rosalind.' (in some versions it reads "let no fair be be kept in mind/ but the fair of Rosalind)
Sorry if that's not what you were thinking of.
I too cannot find a quote that ends with these words, though since you are not completely sure yourself, perhaps it is this line, where your quote appears at the beginning rather than the end. I suspect this may be it, as it is one of the highlights of the scene, as Orlando and Rosalind have finally met in the Forest and he is late.
The line is, "My fair Rosalind, I come within an hour of my promise."
I am including a link to the summary of this act and scene. I hope this is it and it helps!