Scriptures describes this category of angels as follows:
Providers of Priestly Duties
Isaiah 6:1-7 “n the year that king Uzziah died I saw also the Lord sitting upon a throne, high and lifted up, and his train filled the temple. 2 Above it stood the seraphims: each one had six wings; with twain he covered his face, and with twain he covered his feet, and with twain he did fly. 3 And one cried unto another, and said, Holy, holy, holy, is the Lord of hosts: the whole earth is full of his glory. 4 And the posts of the door moved at the voice of him that cried, and the house was filled with smoke. 5 Then said I, Woe is me! for I am undone; because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips: for mine eyes have seen the King, the Lord of hosts. 6 Then flew one of the seraphims unto me, having a live coal in his hand, which he had taken with the tongs from off the altar: 7 And he laid it upon my mouth, and said, Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin purged.”
Revelation 4:8 “And the four beasts had each of them six wings about him; and they were full of eyes within: and they rest not day and night, saying, Holy, holy, holy, Lord God Almighty, which was, and is, and is to come.”
There is not much scripture to describe the seraphim angels. In fact, the only time in scriptures that the word seraphim is used is in Isaiah 6. In Hebrew the word seraphim is the plural word of “saraph,” which means, “to burn.” We find from the passage in Isaiah that these angels resemble a lot like humanity.
We find that what Isaiah describes is an angelic category that praises God but not directly. In other words, they do not directly engage with God but call out to each other in God’s presence.
The words in Isaiah Holy, Holy, Holy are only used twice in scripture. These words are only spoken by Seraphim Angels in both places. When they are spoken, both times, they are spoken to someone transported in a vision to the throne of God.
The fact that the seraphim in Isaiah’s use of a three-fold repetition of God’s holiness is incredibly significant. This is called a “trihagion.” In ancient Judaism, the number “three” signified completeness and stability, connoting God’s wholeness as the beginning, the middle, and the end.
Announcing God’s holiness three times also connotes: