Cassiel is an archangel and the ruling prince in the Seventh Heaven. The Seventh Heaven, which is where God sits on His throne, is considered the holiest of all holies.
Cassiel is often called the angel of tears, the angel of temperance, or the angel who watches over the deaths and burials of kings. He is often referred to as Qafsiel and the ruler of Saturn.
Qaphsiel can be invoked in an ancient Hebrew charm that tells if an enemy is running. Gustav Davidson mentions that Qafsiel, the ruler of the seven heavens in 3 Enoch is Qafsiel. He cites Odeberg’s edition. Odeberg’s edition states that Qafsiel is “(one) of the guardians of the seventh Hall” in Hekhalot Rabbati. Qaspiel, on the other hand, is described by Hekhalot Rabbati in Hekhalot as a guardian at the sixth palace. He is armed with a lightning-dripping blade (which shouts “Ruin!"). Qaspiel also wields a bow, tempests, and light as well as powerful winds–weapons he uses against anyone who is not fit to see God. Qaspiel is described later in the same work as one of the “guardians at the entrance to the seventh palace” along with Dumiel, Gabriel. Ma’aseh Merkavah also lists Qaspiel as the guardian of Qaspiel’s second palace. Sefer Raziel names Qephetzial the prince of Saturn. According to the Zohar, Kafziel is one of two chief aides (alongside Hizikiel).
Cassiel appears in The Sworn Book of Honorius, and (pseudo-)-Peter de Abano’s Heptameron. (The latter was also influenced in part by Sefer Raziel). Cassiel’s presence within Honorius could also be due to Greek influence. He is listed in the Byzantine exorcism manual Kasiel. He is listed in these works as not only the angel over Saturn, but also as the Angel of the North, and one of the Sigillum Dei angels. After Honorius, the Heptameron, and Cassiel, Cassiel is listed in the Liber De Angelis as Cassael (again, the angel over Saturn), then various editions of The Key of Solomon as Cassiel/Cassael and the angel (sometimes archangel), over Saturn or Saturday and again in the Sigillum Dei. Cassiel appears in Francis Barrett’s The Magus, as a dragon-riding jinn wearing a beard and again as an angel over Saturn.