That was Yusuf and I whom/who you saw.

[Anna232]

This sentence is from an exercise in The Blue Book of Grammar and Punctuation by Jane Straus.
Isn't "who" also correct? It is a standalone sentence.

1. That was Yusuf and I whom you saw.

 

[5jj]

The purist would say That was Yusuf and me whom you saw.

Few these days would object to who. Many would drop the relative pronoun: That was Yusuf and me you saw.

 

[PeterCW]

Both "you and me / you and I" and "who / whom" are often confused by native speakers to the point where being "correct" can be derided as pedantry. When writing I have occasionally recast a passage for this reason.