The Angel YHWH Visits Abraham: Rashbam Reworks a Christian Interpretation
Justin Martyr, an early Church Father (c. 100–165 C.E.), interprets the strange appearance of the LORD to Abraham at Mamre as an early instantiation of God the Son, i.e., Jesus. While Rashbam obviously rejected this belief, he learned from this Christian interpretation and suggests that here, the name YHWH refers to an angel, which explains why YHWH speaks about YHWH in this story in the third person.