He had not yet finished speaking, and—look!—Rivkah, the daughter of Besu'el, the son of Milkah, who was the wife of Avraham's brother Nachor, came out, and her pitcher was on her shoulder.
-- Breshis 24:15
What was unique about Eliezer's prayer? (v. 15)
Midrash: Rabbi Shimon bar Yochai said: Three people were answered while their words were still upon their tongues: Avraham's servant Eliezer, Moshe, and Shlomo. Regarding Eliezer, the verse states, "He had not yet finished speaking, and—look!—Rivkah... came out" (v. 15). Regarding Moshe, the verse states, "When he finished speaking all these words [after his authority had been challenged by Korach], the ground split open" (Bamidbar 16:31). Regarding Shlomo, the verse states, "When Shlomo finished speaking to G‑d [at the inauguration of the holy temple], the fire descended from heaven" (Chron. I 7:1).
In fact, it appears that Eliezer's prayer was even greater than that of Moshe or Shlomo, since they were only answered after they finishing speaking, whereas Eliezer "had not yet finished speaking" when Rivkah came out with a pitcher on her shoulder (Bereishis Rabah 60:4; Midrash Seichel Tov)
Eliezer's Prayer (v. 15)
The Midrash cites Eliezer's prayer as one of the greatest in history, since he was answered immediately. In fact, his prayer appears to be even greater than that of Moshe and Shlomo, since Eliezer was answered even before he had finished his prayer.
However, at the literal level of Torah interpretation, it would be difficult to accept that Rivkah's sudden appearance was actually a result of Eliezer's prayer, since she clearly must have departed from home before Eliezer started praying. Thus, her arrival was not caused by Eliezer's prayer at all. What then was the significance of Rivkah's arrival during Eliezer's prayer?
The Explanation
When Avraham sent Eliezer on the mission to find a wife for Yitzchak, he said, "G‑d, the G‑d of the heavens... will send His angel ahead of you, and you will take a wife for my son from there" (above, v. 7). Note that Avraham did not say, "G‑d will send his angel with you," which would suggest a mere "helping hand" of Divine assistance on occasion. Rather, he said, "G‑d... will send his angel ahead of you," indicating that Divine intervention would preempt Eliezer's efforts, ensuring his success.
This preemptive help from above became evident during Eliezer's prayer. The fact that he was answered before he had finished praying indicates that G‑d had orchestrated the events in Eliezer's favor, even before he had begun to pray. This gave Eliezer much encouragement, as he witnessed Avraham's promise of an angel going ahead actually unfold. The Divine providence of Rivkah's appearance, before he had even concluded his prayer, was a first indication to him that this girl was none other than Yitzchak's future wife.
Eliezer's Continued Success
On reading the entire account of Eliezer's mission, we see that he consistently relied on Avraham's promise of preemptive Divine providence and that various supernatural events occurred which precluded problems arising later:
Eliezer's "Adjusted" Report
According to the above explanation—that Eliezer was assisted by an angel going ahead of him—we can explain an interesting point that arises when we read Eliezer's report to Besu'el. Instead of repeating Avraham's words, "G‑d... will send His angel ahead of you," Eliezer told Besu'el that Avraham had said, "G‑d... will send His angel with you and lead your way to success."
Why did Eliezer find it necessary to alter Avraham's words? According to the above explanation, we can understand that Eliezer could not possibly have repeated to Besu'el Avraham's exact words. Saying that "G‑d... will send His angel ahead of you" would have been tantamount to declaring that "I have already been granted success by G‑d." This would have led Besu'el to respond, "If you've already been guaranteed success, then why are you bothering to speak to me?" Therefore, Eliezer was forced to adjust Avraham's words, reporting that the angel had merely accompanied him and provided Divine assistance, rather than telling the truth, that the angel had gone ahead to ensure a Divine guarantee of success.
How could Eliezer credit Avraham with a statement which he did not say?
In fact, Eliezer did tell the truth, but not the whole truth. Eliezer had received Divine assistance, so he told Besu'el that G‑d's angel had helped him (the angel was "with him"). What he did not reveal to Besu'el was the additional fact that G‑d's assistance had been granted to him to the extent that his success was totally disproportionate to his efforts, and had been guaranteed in advance.
(Based on Likutei Sichos vol. 25, p. 99ff.)
An excerpt from the Gutnick Chumash published by Kol Menachem, New York.