Genesis 3:24
23 So the Lord God expelled him from the orchard in Eden to cultivate the ground from which he had been taken. 24 When he drove the man out, he placed on the eastern side of the orchard in Eden angelic sentries who used the flame of a whirling sword to guard the way to the tree of life.
Onkelos Genesis 3:24
23 and the Lord God sent him forth from the garden of Eden to till the ground from where he had been created. 24 And He drove out the man. In early times, he stationed the cherubim, and the sharp sword which revolved to keep the way of the Tree of Life.
Notes and References
"... Bible: mikedem, which could mean 'east' or 'from early times.' Both are in Genesis Rabbah. Our targumist, who borrowed material from this Midrash, opted for the latter interpretation, and suggested that the cherubim and sword were placed at the entrance to the garden before the episode with the tree ... The Hebrew metaphor lahat, 'fiery,' probably refers to an unsheathed sword that flashed brightly in the sun. It could also be a clean, ready-to-use sword. The Aramaic translation captures the intent of the metaphor by using 'sharp.' The sword discourages Adam from returning to the garden (Rashi) ..."
Drazin, Israel, and Stanley M. Wagner Onkelos on the Torah, Genesis: Understanding the Bible Text (p. 21) Gefen, 2006