You can either knit across the neck stitches and then place them on the stitch holder, or you can cut the yarn after binding off the first 26 stitches, leaving a tail long enough to weave in, and then place the neck stitches on a stitch holder and then join another piece of yarn to bind off the last 26 stitches. I think I would go with the first way I mentioned.

I would bind off the first 26 stitches. Cut the yarn leaving a 6-8 inch tail. Put the next 26 stitches on a stitch holder or thread a contrasting piece of yarn through the stitches so they won't unravel. Then take a new piece of yarn and bind off the last 26 stitches, leaving a 6 inch tail at the beginning and end so that you can weave the tails into the sweater when it is done.

Cutting the yarn after the first 26 stitches and weaving in the tail would make a nicer looking sweater, in my opinion, then just knitting across the neck and then putting the stitches on a holder. That would result in the collar being set right on top of the back. It really would look better and fit better if it's set in a bit.

A bit more work, but a more polished result.

Thank you for your help!