This pattern is posted for free on Vickie Howell’s blog (on the Bernat website). There is errata in the Bernat Website version of this pattern. Under “Ribbed slip stitch pattern” (this is the stitch pattern section before the pattern starts) Row 2 should read:

Row 2: Ch 1 (does not count as a st), 1 sl st blo into each st across, turn.
Repeat Row 2 until desired length.

Also throughout the mitt instructions, each time that you work a set of 11 slip stitches, you should be working into ONLY the back loop of each stitch. For example, Row 2 of the instructions should read:

Row 2: Ch 1, 1 sc into first st, 1 sl st into next hdc, 1 hdc into next sl st 9 times, 1 sl st blo into each of next 11 sts, turn.

These errors are only in the version of this pattern posted to the Bernat Blog website.