Avraham warns Eliezer again and again: Don’t let my son Yitzchok ever marry a Canaanis! Even if Eliezer cannot find for him a suitable shidduch in Aram; still, a Canaani woman is NEVER an option, even Bedi'eved. Why is Avraham Avinu so strong about this? RSRH Zatzal says that Canaanim were lacking in morals. This affects everything, and lowers the person completely, Rachmana Litzlan.
Notice how Avraham Avinu is called: נְשִׂיא אֱלֹקִים אַתָּה בְּתוֹכֵנוּ “a prince” by: נְבְיְחְת Bnei Chais, and how Eliezer is called: הַמָּשֵׁל בְּכָל אֲשֶׁר לוֹ “a ruler”! We see how although Eliezer was an Eved (slave), Avraham Avinu still made him important. RSRH Zatzal says that the reason why Hagar couldn’t be Mach'nia to Sara was because Avraham Avinu was so distant from the mentality of slavery, that Hagar’s marriage made her feel like an equal. We see how Avraham Avinu was complete Romemus, just like his name, “Av-Ram”.
And the descendants of Avraham Avinu are all: מַמְלֶכֶת כֹּהֲנִים – a kingdom of princes. (Rashi). When Moshe Rabeinu was first told that Hashem wants to take us out of Mitzrayim, the very first thing Hashem said was: בְּנִי בְּכוֹרִי יִשְׂרָאֵל (שמות ד כב) – the Yidden are my “Bechor”. Rashi explains that “Bechor” means “prominence”; i.e., even though they may be slaves right now, they are not really: עַבְדִּים slaves in their essence. This is the best way to free a slave; by telling him that he isn’t: שַיֵּךְ relevant to slavery, since he is an Adam Gadol and a: שַׂר prince!
