Gauge
I don’t as a rule do gauge swatches. I used a worsted weight yarn with size 6 needles to make a bag that measures 7” width and 8” length - your results may vary...
Abbreviations
k: knit
k2tog: knit 2 stitches together
p: purl
inc: K into front and back of stitch
sl: slip
st/sts: stitch/stitches
4 stc: 4 stitch cable
18 stc: 18 stitch cable
C4F: sl 2 sts onto cable needle at front, k2, k2 from cable needle
C5F: sl 3 sts onto cable needle at front, k2, sl p st back onto LH needle and p it, k2 from cable needle
C5B: sl 3 sts onto cable needle at back, k2, sl p st back onto LH needle and p it, k 2 from cable needle
Pattern
(Note: I slip the first stitch of each row, to make the selvedges easier to seam)
Cast on 41 stitches
Row 1-5: Work five rows of k1, p1 ribbing
Row 6: Sl 1, k2, inc, k3, inc across to last 4 stitches, k4 (50 sts)
Row 7: (and all “odd” rows of cable section): Sl 1, p3, k1, p2, 4stc, p2, k1, p2, 18stc, p2 k1, p2, 4stc, p2, k1, p4
Row 8: (and all “even” rows of cable sections): k all stitches that were purled on the odd rows and purl all stitches that were knitted on the odd rows.
Rows 9-50: Follow pattern for the 4stc and the 18stc for 42 more rows
Row 51: Sl 1 k3, k2tog across to last 4 stitches, k45 (41 stitches)
Row 52-56: k1, p1 ribbing for 5 rows
Row 57: Bind off
4 Stitch Cable
Rows 1 and 3: k4
Rows 2,4,6: p4
Row 5: C4F
Repeat these 6 rows
18 Stitch Cable
Row 1: p2, (k2, p1) 5 times, p1
Row 2, 4,6,8: (p2, k1) 5 times, k1
Row 3: p2,k2, (p1C5F) twice, p2
Row 5: as row 1
Row 7: p2, (C5B, p1) twice, k2, p2
Repeat these 8 rows
Assembly
With the cable sides facing one another, sew the two panels together (“inside out”), starting at what will be the “top” of the purse and working down one side, across the “bottom”, then up the remaining “side”.
For the strap, I used a knitting spool to knit a cord to my desired length. For the closure, I crocheted a loop and attached it to the center of the inside of the “back” panel, then stitched a large button to the center of the top ribbing of the “front” panel.
References
Compton, Claire. 2004. The Knitters Bible. 108-110 (4 Stitch Cable and 5 Rib Braid).