Is trimming of hair and nails between 1st and 10th of Zil Hajj a sin? And does it invalidate our scarifice?

I have heard from some of my friends that it is forbidden to trim hair or nails from 1st Zil Hajj to 10 Zil Hajj if one is offering a sacrifice. So I did some research and came to know that Muhammad (PBUH) actually said that we shouldn't trim our hair or nails if offering a sacrifice. But I'm a little confused because Islam taught us to be clean and neat. Since it is a Sunnah so will cutting my nails or hair affect the validity of my sacrifice or makes me a sinner?