The earliest known description of 'Cat' pose (to date) is called Mārjārottānāsana (Upturned Cat Pose), which is described in the yoga text called the Haṭhābhyāsapaddhati (17th - 18th century). The image seen here is an artistic representation from the 19th-century royal digest named the Śrītattvanidhi.
Unlike the version of 'Cat' pose commonly practised in Modern Postural Yoga (i.e. flexing the spine while in a kneeling position), this particular āsana is practised in the supine position and requires quite a bit of muscular effort in the abdomen to achieve the movement of knees to ears. When practised repetitively, it becomes an abdominal oblique strengthening posture.
The description of this āsana immediately follows that of Śvottānāsana - 'Upturned Dog Pose'.
"Having positioned [himself] like an up-turned dog, [the yogin] should touch both knees with his ears in turn. [This is] the up-turned cat [pose]."
Translation by Jason Birch (2015)
As the text links one āsana to the next, the Haṭhābhyāsapaddhati is the only pre-modern yoga text known today to provide what appears to be a sequenced practice as well as āsana that involve repetitive movement rather than just the static seated postures described in earlier Haṭhayoga texts.