Eliezer certainly made a bracha on the water before drinking. Therefore, Rivkah knew that she couldn’t give it to the donkeys. For this reason, she emptied the vessel and drew new water for the camels.
Spilling the Water for Eliezer’s Honor:
The Shlah Hakadosh writes that we can learn a lesson from Rivkah about how much one must respect all people.
After Eliezer and his men drank from the pitcher, a little bit of water remained. Rivkah didn’t know what to do with it because if she gave it to the camels, it would be insulting to the men, as it would seem like she was giving equal value to them and the camels. If she would spill it out, it would also be an insult, as it would seem like she was saying that water left in a pitcher they drank from is garbage. Therefore, she ran towards the well and dropped the pitcher, making it look like she spilled the rest of the water accidentally and had to draw more. This left the men with their honor and avoided insulting them.
Taking Care With Kovod Habriyus:
Harav Avrohom Genichovsky zt”l, Rosh Yeshivas Tchebin, was known for the tremendous care he took to honor all people and to never cause anyone even a bit of embarrassment. He once accompanied a bochur who had an appointment with a psychiatrist. In the waiting room, he met a Yid that he knew. It goes without saying that the man didn’t want anyone to see him there. Without missing a beat, Rav Avrohom ran over to the man and tearfully said to him, “Please don’t tell anyone that you saw me coming here for my appointment....”
תֶּן לוֹ צֹאן וּבָקָר וגו' (כד, לה)
גְדָּל וַיִּ וַה' בֵּרַ ךְ אֶת אֲדֹנִי מְ אֹד וַיִּ
And Hashem blessed my master very much and he became great, and He gave him sheep and cattle... (24:35)
Hashem Blessed Him With the Middah of Anavah:
The Bais Avrohom of Slonim zy”a translates the pasuk as saying that “Hashem blessed Avrohom with me’od.” He explains this to mean that He blessed him with the middah of “me’od me’od havei shafal ruach (Avos 4:4).” Be very, very lowly of spirit. “And he became great” in the merit of this humility.
It then says that “Avrohom gave everything that was to him (lo) to Yitzchok.” The Bais Avrohom notes that it doesn’t say that he gave everything he had to Yitzchok. Rather, it says he gave “everything that was to him” to Yitzchok. He translates this to mean that he gave his “lo” – his nothingness – to Yitzchok, meaning that he passed his trait of humility along to him.
He goes on to quote an explanation from the Kozhnitzer Rebbe zy”a on the pasuk in Tehillim (138:6) ”For Hashem is high but He sees the lowly, and He chastises the haughty from afar.” Hashem is very lofty, and only those who consider themselves lowly are able to connect to him and “see” Him. One who is haughty, however, cannot see Him for up close. He can only view Him from a distance.
וְיִצְחָק בָּא וגו' בְּאֵר לַחַי רֹאִ י וְהוּא יוֹשֵׁב בְּאֶרֶ ץ הַנֶּגֶב (כד, סב)
And Yitzchok came... from B’er Lachai Ro’i, and he dwelt in the land of the south. (24:62)
Recognizing Hashem’s Guidance Creates Simcha:
Rav Henoch of Alexander zy”a (Sefer Chashbah L’Tova) explains this pasuk by saying that it is known that a person who recognizes that Hashem is always overseeing whatever he does will naturally be happy. Thus, the pasuk is saying: “V’Yitzchok bah.” Happiness comes to a person. (The word ”Yitzchok” represents happiness and laughter as is seen from Bereishis 21:6.) Where does this happiness come from? From “Be’er Lachai Ro’i.” A person attains this joy when he recognizes that Hashem is watching him. (The word “ro’i” indicates ”watching”.) Even if a person “dwell in the land of the negev”, i.e., a dry and desolate place, and he possesses nothing, Hashem is still always overseeing him.
When one knows this, he will be happy.