The text’s focus is on the content of the seraphim’s chant. Young (I:241, n. 17) explains that this verb, as used here carries frequentative force, meaning, that this chant or call is repeated over and over. The word “Holy” is repeated three times for emphasis (many have related the three-fold repetition to the three person of the Trinity but that is more than the text will support).
The word “holy” relates God’s “otherness,” his differences from and distinction from his creatures and creation. God is involved in his creation, but, unlike the eastern mystical religions (and Star Wars) God is independent from his creation.
This word “holy” also carries an ethical dimension to it. God is wholly distinct and separate from sin and what is sinful. His eyes cannot even look upon iniquity. This innate and intrinsic holiness is why God is the standard of holiness, not because of his might or sovereignty, but because this is an integral and vital part of his own being and character.
Of all the attributes of God, this is the one the seraphim set forth as God’s distinguishing characteristic. The repetition of this word “holy” emphasizes not only its importance in terms of our recognition, but also our worship. It also reminds us that deep and sustained reflection on the Lord’s holiness is essential for those who seek to worship and serve the Lord.
That this vision’s emphasis on the Lord’s holiness made an impact on Isaiah is evident in his use of the title “The Holy One of Israel.” As Young points out, this title is used only six times in the OT, two of which are clearly influenced by Isaiah’s usage. Isaiah, however, uses this title twelve times in chapters 1-39 and fourteen times in chapters 40-66.