“And it shall be that the young woman to whom I say, ‘Please let down your pitcher that I may drink,’ and she shall say, ‘Drink, and I will also give your camels drink,’ let her be the one You have designated for Your servant Yitzchak; and by this I shall know that You have dealt kindly with my master.” (Bereshit 24:14)
The Talmud (Ta’anit 4a) teaches: “Three people made inappropriate requests, but two of them were answered favorably, and one unfavorably... Eliezer, the servant of Abraham, [was answered favorably,] as it is written: ‘And the daughters of the men of the city... and it shall be that the young woman to whom I say...’ It could have been a lame or blind woman, but he was answered well, and Rivkah was presented to him.”
We may ask: Why did Eliezer rely on a miracle, especially in so crucial a matter?
We can say this: The Midrash (quoted by Rashi, v. 42) explains that Eliezer said, “Today I departed and today I arrived,” which implies that the earth contracted miraculously before him (kefitzat haderech). Eliezer therefore reasoned: “If a miracle has already occurred for me, it must be that Hashem desires to perform another one,” and thus he relied upon it.
The reason he desired a miracle was that Rivkah was only three years old (Rashi on 25:20), and Eliezer feared that her father, Betuel, would object to the marriage, claiming that it was forbidden to marry off such a young child before she was mature enough to say, “I wish to marry this man,” as taught in the Talmud (Kiddushin 41a). Therefore, he wanted the encounter to occur through an obvious miracle so that this objection would carry no weight.
The reason for the prohibition of marrying off a very young girl is the concern that when she grows up, she may not want that husband, and “we do not rely on miracles” to determine such a matter. But in this case, since Hashem performed multiple miracles to unite Rivkah and Yitzchak, it was clear that their union was decreed from Heaven. Hence, there was no longer any fear that Rivkah would later refuse him, for everything had occurred miraculously in fulfillment of the Divine will. Thus, Betuel could not reject Eliezer’s proposal.
(Zera Shimshon, Parashat Chayei Sarah, art. 9)