Moshe’s leadership did not begin with a great level of knowledge or a proven track record as a prophet. Rather it began with solid midot (personal attributes). One of the moments that demonstrated Moshe’s fine qualities was when he saved the daughters of Yitro from the abusive shepherds and gave their flock to drink. Moshe, who had spent decades being pursued (see Ramban to Shemot 2:21) was not afraid to take on powerful majorities, and as a result, his reward was soon to follow. Yitro offered Moshe to live with him. The pasuk describes some type of acceptance on Moshe’s part, which then lead to his marrying Yitro’s daughter, Tzippora. However, the exact meaning of the word "vayo’el," the verb for "____ to live with the man" (Shemot 2:21) is allusive.
The Targum, cited by Rashi in his first explanation, says that the word means to acquiesce. The most difficult element of that explanation is that it seems quite natural and thus superfluous to mention that he agreed to the gracious offer. A midrash says that the word means that he lived with them, and another says that it means that he began, in this case, to shepherd Yitro’s flock. Again, why would such details be instructive regarding the Torah’s presentation of the events?
Let us turn to Rashi’s second explanation, one which he describes as homiletic. Rashi says that vayo’el comes from the word alah, which means oath. In other words, Moshe swore that he would not leave Yitro’s home without permission. One of the advantages of this explanation is that there are many appearances of this root with this meaning throughout Tanach. It is also of particular note that Yitro had demanded and Moshe had agreed to quite a commitment, one which shows the degree to which Moshe was willing to go to return good to those who were willing to do good for him.
The midrash (Devarim Rabba 11) analyzes a Psalm that we say regularly, from the perspective of the qualities of Moshe: "Who will go up on the mountain of Hashem and who will stand in the place of His sanctity? One with clean hands and a pure heart who will not raise My soul [in oath] for naught and will not swear for trickery. He will receive a blessing from Hashem and righteousness from the G-d of his salvation." (Tehillim 24: 3-5). This refers to Moshe who went up to the holy Mount Sinai and was the recipient of special blessings, not only for himself but for others who were affected by him. The midrash identifies the distancing from an insincere oath as a reference to Moshe’s oath to stay with Yitro.
Blessed is a nation which is led by one who keeps his promises to the fullest. We pray that we will be led by those with such qualities