As I was reading the weekly portion Chayei Sarah, it caught my attention that Eliezer's promise is repeated many times.
When Eliezer leaves to get a wife for Isaac, he promises (Bereishit 24:14):
So let it come to pass, that the damsel to whom I shall say: Let down thy pitcher, I pray thee, that I may drink; and she shall say: Drink, and I will give thy camels drink also; let the same be she that Thou hast appointed for Thy servant, even for Isaac; and thereby shall I know that Thou hast shown kindness unto my master.'
He seems to be fortunate, because Rebecca gives him water (Bereishit 24:18–19):
And she said: 'Drink, my lord'; and she hastened, and let down her pitcher upon her hand, and gave him drink. And when she had done giving him drink, she said: 'I will draw for thy camels also, until they have done drinking.'
Then Eliezer tells Betueil the story of his promise (Bereishit 24:43–44):
Behold, I stand by the fountain of water; and let it come to pass, that the maiden that cometh forth to draw, to whom I shall say: Give me, I pray thee, a little water from thy pitcher to drink; and she shall say to me: Both drink thou, and I will also draw for thy camels; let the same be the woman whom the LORD hath appointed for my master's son.
And he says that indeed, everything happened as he hoped (Bereishit 24:45–46):
And before I had done speaking to my heart, behold, Rebekah came forth with her pitcher on her shoulder; and she went down unto the fountain, and drew. And I said unto her: Let me drink, I pray thee. And she made haste, and let down her pitcher from her shoulder, and said: Drink, and I will give thy camels drink also. So I drank, and she made the camels drink also.
In general, the Torah does not contain superfluous words, but here the story is repeated four times. Why? Are there any commentaries discussing this issue?