Hello and Thank you for taking thus question.
I borrowed a sefer from my friend (The radiance of Shabbos by R’ Simcha Bunim Cohen) the sefer was is Like new condition. One of my children spilled some water on it causing some water damage to some of the pages. I decided I’ll order my friend a new one from amazon and I’ll keep the water damaged one.
When the new one arrived it was the “new expanded edition” (published in 2021 not 2010) The notes have much greater detail, an added chapter or two, it is 235 pages as opposed to 180, it is significantly better in my opinion, I’m not sure if it would actually sell for more on the open market. I am happy for my friend to receive the expanded version, would it be ribbis for me to give it to him? If so what would be the most practical way of “making him whole again”
Thank you for your question.
You are allowed to return the new edition of the sefer, and you don’t have to be concerned about ribbis here. Ribbis generally applies when one person lends money or something else with the intention that the money or food item will be used, and then something else will be returned in its place. In your question, you borrowed the sefer in order to return the actual sefer itself, therefore the halachos of ribbis will not apply.
Yoreh Deah 177-19.