Wondering about her unusual pregnancy, Rivka seeks help. “Va’telech lidrosh et Hashem” (Bereishit 25:23). Rashi explains that she goes to Shem to hear prophecy
about her future offspring. Ramban disagrees arguing that “drishat Hashem” refers to prayer, not prophecy. Tehillim 34:5, which we say every Shabbat morning, talks of God responding and saving the person who was doresh Him. In that context, the phrase clearly refers to supplication. Ramban contends that Amos 5:4 and Yechezkel 20:3 further establish the point. According to Ramban, Rivka travelled for the purpose of prayer.
Rashi’s approach does not lack biblical backing. Rabbenu Nissim Gerondi (Derashot haRan Derasha 2) notes that the king of Aram uses the identical phrase when he want Elisha to inform him whether or not he will recover from an illness (Melachim II 8:8). Achazya, king of Israel, uses the verb “darash” when he asks a pagan god if his sickness will prove fatal (Melachim II 1:2). These verses supports Rashi’s contention that Rivka went in search of prophecy.
Fortunately, another passage in Ramban’s commentary explicitly addresses these verses. Moshe tells his father-in-law that the people stand and wait to see him in order “li’drosh Elokim” (Shmot 18:15). Rashi explains that the people expect Moshe to hear information, Torah, from God. Once again, Ramban disagrees and says that they want Moshe to pray for their sick. He also cites the verse about the king of Aram and offers a novel interpretation.
“And the king said unto Chazael: Take a present in your hand, and go meet the man of God, and inquire of the Lord by him, saying: Shall I recover of this sickness?”
The end of this verse indicates that the inquiry relates to information from above. As Rabbenu Nissim noted, this bolsters Rashi’s reading of “derishat Hashem.” Ramban thinks that the Aramean king wanted Elisha to pray on his behalf and further convey if those prayers were accepted. This reading concedes that the prophet would have privileged information but it shifts the focus to the act of prayer.
Netziv adds an argument in favor of Rashi’s approach. It makes sense that Rivkah would need to travel to speak to a prophet but why should she have to leave home to pray? A person can pray anywhere; indeed, Yitzhak’s prayers for a child are answered affirmatively in that very spot.
Given Netziv’s point and given the simplest reading of the verses in Sefer Melachim, what motivated Ramban to reject Rashi’s interpretation? I would like to offer a speculative answer that works for the Rivka context. Perhaps Ramban thought that the truly righteous search for God must involve more than just the search for information; it must include acts of mitzva. Rivka does not merely want to see an oracle; she converses with her maker in the act of prayer.